US President Joe Biden said on Tuesday he would consider personal sanctions on President Vladimir Putin if Russia invades Ukraine, as Western leaders stepped up military preparations and made plans to shield Europe from a potential energy supply shock.

The rare sanctions threat came as NATO places forces on standby and reinforces eastern Europe with more ships and fighter jets in response to Russia's troop build-up near its border with Ukraine.

Russia denies planning an attack and says the crisis is being driven by NATO and US actions. It is demanding security guarantees from the West, including a promise by NATO never to admit Ukraine. Moscow sees the former Soviet republic as a buffer between Russia and NATO countries.

Following multiple rounds of US-Russia talks over Ukraine that failed to reach a breakthrough, Biden, who has long warned Moscow of economic consequences, upped the ante on Tuesday by saying Putin could personally face sanctions.

If Russia were to move into Ukraine with the estimated 100,000 soldiers it has massed near the border, Biden said it would be the "largest invasion since World War Two" and would "change the world."

Speaking to reporters, Biden was asked if he would see himself imposing sanctions on Putin directly if Russia invaded Ukraine. "Yes," he responded. "I would see that."

Direct US sanctions on foreign leaders are rare but not unprecedented. Others who have faced sanctions include Venezuela's Nicolas Maduro, Syria's Bashar al-Assad and Libya's Muammer Gaddafi.

On Tuesday, a US plane carrying military equipment and munitions landed in Kyiv, the third installment of a $200 million package to shore up Ukraine's defenses.

The Pentagon has put on alert about 8,500 US troops in Europe and the United States to be ready to deploy to NATO's eastern flank if needed.

Russia said it was watching with great concern and accused Washington of fuelling tensions over Ukraine, repeating its line that the crisis was being driven by US and NATO actions rather than by its own build-up of forces near the Ukrainian border.

Biden said on Tuesday he may deploy US troops in the nearer term but ruled out sending unilateral US forces to Ukraine, which is not a NATO member.

"There is not going to be any American forces moving into Ukraine," he said.

So far, NATO has about 4,000 troops in multinational battalions in Estonia, Lithuania, Latvia and Poland, backed by tanks, air defenses and intelligence and surveillance units.

As Western leaders appeal for unity, differences have emerged among European nations over how best to respond. Putin is due to meet Wednesday with the heads of some of the biggest companies in Italy, Russia's fifth biggest trading partner, despite the rising tensions.

"It is absolutely vital that... the West is united now, because it is our unity now that will be much more effective in deterring any Russian aggression," British Prime Minister Boris Johnson said, adding Britain was discussing with the United States the possibility of banning Russia from the SWIFT global payments system.

French President Emmanuel Macron said he would seek clarification over Russia's intentions in a phone call with Putin set for Friday. Political advisers from Russia, Ukraine, Germany and France are due to meet in Paris on Wednesday.

GAS DIVERSION PLANS

With fears of a new Russian military assault high after its invasion of Crimea in 2014, Ukrainian President Volodymyr Zelenskiy urged his compatriots on Tuesday to stay calm and said work was underway to bring about a meeting between him and the leaders of Russia, Germany and France.

"There are no rose-colored glasses, no childish illusions, everything is not simple. ... But there is hope," Zelenskiy said in a televised address. "Protect your body from viruses, your brain from lies, your heart from panic."

In Washington, senior Biden administration officials said the United States was in talks with major energy-producing countries and companies around the world over a potential diversion of supplies to Europe if Russia invades Ukraine.

The EU depends on Russia for around a third of its gas supplies. Any interruptions to its Russian imports would exacerbate an existing energy crisis caused by shortages.

"We've... been working to identify additional volumes of non-Russian natural gas from North Africa and the Middle East, Asia, and the United States," White House spokesperson Jen Psaki told reporters.

"We're in discussion with major natural gas producers around the globe to understand their capacity and willingness to temporarily surge natural gas output and to allocate these volumes to European buyers," she said.

Psaki and other officials did not name specific countries or companies but said they included a broad range of suppliers, including sellers of liquefied natural gas (LNG).

An escalated conflict would likely further increase energy costs for many countries, keeping headline inflation rates elevated for longer, said Gita Gopinath, first deputy managing director of the International Monetary Fund.

Tesla CEO Elon Musk gave the strongest hint yet Monday that he would like to pay less for Twitter than his $44 billion offer made last month.

Musk told a Miami technology conference that a viable deal at a lower price would not be out of the question, according to a report by Bloomberg News, which said it viewed a livestream video of the conference posted by a Twitter user.

Also at the All in Summit, Musk estimated that at least 20% of Twitter's 229 million accounts are spam bots, percentage he said was at the low end of his assessment, according to the report.

The appearance came a few hours after Musk began trolling Twitter CEO Paraj Agrawal, who posted a series of tweets explaining his company's effort to fight bots and how it has consistently estimated that less than 5% of Twitter accounts are fake.

In all, the day's events bolstered theories from analysts that Musk either wants out of the deal or is seeking a lower price, largely due to a huge decline in value of Tesla stock, some of which he has pledged to finance the Twitter acquisition.

Twitter shares closed Monday down just over 8% at $37.39, below where the stock was just before Musk disclosed that he was Twitter's largest shareholder. Musk made the offer to buy Twitter for $54.20 per share on April 14.

On Friday Musk tweeted that his plan to buy Twitter was placed on temporary hold as he tried to pinpoint the number of fake accounts on the social media platform. The Tesla and SpaceX CEO said the hold was pending details of Twitter's calculation that fake accounts are less than 5% of its users.

In tweets on Monday, Agrawal acknowledged Twitter isn't perfect at catching spam. He wrote that every quarter, the company has made the estimate of less than 5% spam. “Our estimate is based on multiple human reviews of thousands of accounts that are sampled at random, consistently over time,” Agrawal wrote.

Estimates for the last four quarters were all well under 5%, he wrote. “The error margins on our estimates give us confidence in our public statements each quarter.”

Musk, using his favorite platform, responded with a smiling emoji of poop, then asked how Twitter's advertisers know what they're getting for their money.

Tesla shares closed Monday down nearly 6% at $724.37. They have lost about one-third of their value since the trading day before Musk disclosed his Twitter stake.

Musk did not immediately return messages seeking comment. The All in Summit said in an email that it would post the video of Musk's appearance in the coming days.

- AP/UNB

The overall number of Covid cases is now fast approaching 522 million amid a rise in new infections in parts of the world.

According to Johns Hopkins University (JHU), the total case count mounted to 521,911,280 while the death toll from the virus reached 6,265,362 Tuesday morning.

The US has recorded 82,613,628 cases so far and 999,841 people have died from the virus in the country, the data shows.

India's Covid-19 tally rose to 43,124,879 on Monday with 1078 new cases registered in 24 hours, showed the health ministry data.

Besides, 27 deaths from the pandemic registered across the country since Saturday morning took the total death toll to 524,241.

North Korea has mobilised its military to distribute Covid medications and deployed more than 10,000 health workers to help trace potential patients as it fights a sweeping coronavirus wave, state media KCNA said on Tuesday.

The isolated country is grappling with its first acknowledged Covid-19 outbreak, which it confirmed last week, fuelling concerns over a major crisis due to a lack of vaccines and adequate medical infrastructure. 

The state emergency epidemic prevention headquarters reported 269,510 more people with fever symptoms, bringing the total to 1,483,060, while the death toll grew to 56 as of Monday evening, KCNA said. It did not say how many people have tested positive for Covid-19.

"A powerful force" of the army's medical corps was immediately deployed to improve the supply of medicines in the capital Pyongyang, the centre of the epidemic, following an order by leader Kim Jong Un, KCNA reported.

The team's mission was aimed at "defusing the public health crisis" in Pyongyang, it said.

Some senior members of the ruling Workers' Party's powerful politburo visited pharmacies and medicine management offices to check supply and demand, KCNA said in another dispatch, after Kim criticised ineffective distribution of drugs.

"They called for establishing a stricter order in keeping and handling the medical supplies, maintaining the principle of prioritising the demand and convenience of the people in the supply," KCNA said.

Tracing efforts were also intensified, with some 11,000 health officials, teachers and medical students joining an "intensive medical examination of all inhabitants" across the country to locate and treat people with fever.

Still, various sectors of the national economy are maintaining production and construction, while taking thorough anti-virus measures, KCNA added. Kim had ordered that limited activity be allowed in each city and county.

The World Health Organization (WHO) has warned the virus may spread rapidly in North Korea, which had no vaccination programme and declined international help. 

South Korea offered working-level talks on Monday to send medical supplies, including vaccines, masks and test kits, as well as technical cooperation, but said the North had not acknowledged its message.

The US State Department said it was concerned about the outbreak's potential impact on North Koreans, and supports vaccine aid to the country.

"To this end, we strongly support and encourage the efforts of US and international aid and health organisations in seeking to prevent and contain the spread of Covid-19 ... and to provide other forms of humanitarian assistance to vulnerable groups in the country," a spokesperson said.

The spokesperson confirmed that the US envoy for North Korea, Sung Kim, had a phone call with South Korea's new nuclear negotiator, Kim Gunn, without elaborating. - Reuters

Ukraine's military said on Tuesday it was working to evacuate all remaining troops from their last stronghold in the besieged port of Mariupol, ceding control of the city to Russia after months of bombardment.

The evacuation likely marked the end of the longest and bloodiest battle of the Ukraine war and a significant defeat for Ukraine. Mariupol is now in ruins after a Russian siege that Ukraine says killed tens of thousands of people in the city.

With the rest of Mariupol firmly in Russian hands, hundreds of Ukrainian troops and civilians had holed up beneath the city's Azovstal steelworks. Civilians inside were evacuated in recent weeks, and more than 260 troops, some of them wounded, left the plant for Russian-controlled areas late on Monday.

"The 'Mariupol' garrison has fulfilled its combat mission," the General Staff of Ukraine's Armed Forces said in a statement announcing evacuations.

"The supreme military command ordered the commanders of the units stationed at Azovstal to save the lives of the personnel... Defenders of Mariupol are the heroes of our time," it added.

Ukraine's deputy defence minister said 53 injured troops from the Azovstal steelworks were taken to a hospital in the Russian-controlled town of Novoazovsk, some 32 kilometres (20 miles) to the east.

Another 211 people were taken to the town of Olenivka, in an area controlled by Russian-backed separatists, Deputy Defence Minister Anna Malyar said. All of the evacuees will be subject to a potential prisoner exchange with Russia, she added.

It was not clear how many troops remained in Azovstal. Ukraine's military said efforts were under way to evacuate those still inside.

Reuters saw five buses carrying troops from Azovstal arrive in Novoazovsk late on Monday. Some of the evacuated troops were wounded and carried out of the buses on stretchers. Some 600 troops were believed to have been inside the steel plant.

"We hope that we will be able to save the lives of our guys," Ukraine President Volodymyr Zelenskiy said in an early morning address. "There are severely wounded ones among them. They're receiving care. Ukraine needs Ukrainian heroes alive."

Arriving in Novoazovsk in a bus marked with Z, a symbol for Russia's invasion, men could be seen stacked on stretchers on three levels. They stared out the windows without reacting. One man was wheeled out, his head tightly wrapped in thick bandages.

Since Russia launched its invasion in February, Mariupol's devastation has become a symbol both of Ukraine's resistance and of Russia's willingness to devastate Ukrainian cities that hold out.

The first evacuations late on Monday came hours after Russia said it had agreed to evacuate wounded Ukrainian soldiers to a medical facility in Novoazovsk.

LVIV EXPLOSIONS, KHARKIV FIGHTING

Moscow calls its nearly three-month-old invasion a "special military operation" to rid Ukraine of fascists, an assertion Kyiv and its Western allies say is a baseless pretext for an unprovoked war.

Russia's invading forces have run into apparent setbacks, with troops forced out of the north and the environs of Kyiv in late March. A Ukrainian counterattack in recent days has driven Russian forces out of the area near Kharkiv, the biggest city in the east.

Areas around Kyiv and the western city of Lviv, near the Polish border, have continued to come under Russian attack. A series of explosions struck Lviv early on Tuesday, a Reuters witness said. There were no immediate reports of casualties or damage.

On Monday, Ukraine's defence ministry troops had advanced all the way to the Russian border, about 40 km north of Kharkiv.

The successes near Kharkiv could let Ukraine attack supply lines for Russia's main offensive, grinding on further south in the Donbas region, where Moscow has been launching mass assaults for a month yet achieving only small gains.

PUTIN CLIMBDOWN OVER NATO

Russian President Vladimir Putin appeared on Monday to climb down from threats to retaliate against Sweden and Finland for announcing plans to join the U.S.-led NATO military alliance.

"As far as expansion goes, including new members Finland and Sweden, Russia has no problems with these states - none. And so in this sense there is no immediate threat to Russia from an expansion to include these countries," Putin said.

The comments appeared to mark a major shift in rhetoric, after years of casting NATO enlargement as a direct threat to Russia's security, including citing it as a justification for the invasion of Ukraine itself.

Soon before Putin spoke, Russia's deputy foreign minister, Sergei Ryabkov, said Finland and Sweden were making a mistake that would have far-reaching consequences: "They should have no illusions that we will simply put up with it."

Putin said NATO enlargement was being used by the United States in an "aggressive" way to aggravate an already difficult global security situation, and that Russia would respond if the alliance moves weapons or troops forward.

"The expansion of military infrastructure into this territory would certainly provoke our response. What that (response) will be - we will see what threats are created for us," Putin said.

Finland and Sweden, both non-aligned throughout the Cold War, say they now want the protection offered by NATO's treaty, under which an attack on any member is an attack on all.

"We are leaving one era behind us and entering a new one," Swedish Prime Minister Magdalena Andersson said, announcing plans to formally abandon militarily non-aligned status - a cornerstone of national identity for more than 200 years.

- Reuters

For construction worker Yogendra Tundre, life at a building site on the outskirts of the Indian Capital New Delhi is hard enough. This year, record high temperatures are making it unbearable.

As India grapples with an unprecedented heatwave, the country's vast majority of poor workers, who generally work outdoors, are vulnerable to the scorching temperatures.

"There is too much heat and if we won't work, what will we eat? For a few days, we work and then we sit idle for a few days because of tiredness and heat," Tundre said.

Temperatures in the New Delhi area have touched 45 degrees Celsius (113 Fahrenheit) this year, often causing Tundre, and his wife Lata, who works at the same construction site, to fall sick. That in turn means they lose income.

"Because of heat, sometimes I don't go to work. I take days off... many times, fall sick from dehydration and then require glucose bottles (intravenous fluids)," Lata said while standing outside their house, a temporary shanty with a tin roof.

Scientists have linked the early onset of an intense summer to climate change, and say more than a billion people in India and neighbouring Pakistan were in some way at risk from the extreme heat.

India suffered its hottest March in more than 100 years and parts of the country experienced their highest temperatures on record in April.

Many places, including New Delhi, saw the temperature gauge top 40 degrees Celsius. More than two dozen people have died of suspected heat strokes since late March, and power demand has hit multi-year highs.

Prime Minister Narendra Modi has called on state governments to draw up measures to mitigate the impact of the extreme heat.

Tundre and Lata live with their two young children in a slum near the construction site in Noida, a satellite city of New Delhi. They moved from their home state of Chhattisgarh in central India to seek work and higher wages around the capital.

On the construction site, labourers scale up walls, lay concrete and carry heavy loads, using ragged scarves around their heads as protection against the sun.

But even when the couple finish their day's work, they have little respite as their home is hot, having absorbed the heat of the sun all day long.

Avikal Somvanshi, an urban environment researcher from India's Centre for Science and Environment, said federal government data showed that heat stress was the most-common cause of death, after lightning, from forces of nature in the last twenty years.

"Most of these deaths occur in men aged 30-45. These are working class, blue-collar men who have no option but to be working in the scorching heat," Somvanshi said.

There are no laws in India that prevent outdoor activity when temperatures breach a certain level, unlike in some Middle-Eastern countries, Somvanshi said.

- Reuters