President Biden and Ukrainian President Volodymyr Zelenskyy spoke for more than 30 minutes Tuesday as the leader in Kyiv pleaded with the West to help him repel Russian invaders.

“Just had a conversation with @POTUS. The American leadership on anti-Russian sanctions and defense assistance to Ukraine was discussed. We must stop the aggressor as soon as possible. Thank you for your support!” Mr. Zelenskyy tweeted.

The White House said the call lasted more than 30 minutes. 

“President Biden underscored the United States’ sustained help for Ukraine, including ongoing deliveries of security assistance, economic support, and humanitarian aid,” the White House said in a readout of the call. “The leaders discussed how the United States, along with allies and partners, is working to hold Russia accountable, including by imposing sanctions that are already having an impact on the Russian economy.  The leaders discussed Russia’s escalation of attacks on sites used by civilians in Ukraine, including today’s bombing near Babyn Yar Holocaust memorial.”

Mr. Biden has ruled out providing ground troops to Ukraine but joined western allies in imposing crippling sanctions on Moscow, hoping the economic squeeze will make Russian President Vladimir Putin rethink an invasion that is featuring bombardments in key cities and killing civilians.

Also Tuesday, Vice President Kamala Harris spoke individually to five leaders on NATO’s eastern flank: Prime Minister Kaja Kallas of Estonia; Prime Minister Krisjanis Karins of Latvia; Prime Minister Ingrida Simonyte of Lithuania; Prime Minister Mateusz Morawiecki of Poland; and Prime Minister Nicolae Ciuca of Romania.

They discussed the response in Ukraine, including the outflow and resettlement of refugees from the war.

“The vice president and the European leaders reviewed recent and upcoming U.S. and NATO force posture adjustments in Europe, including the deployment of thousands of U.S. troops and critical capabilities to reinforce our deterrence posture and collective defense. In each call, the vice president reaffirmed our ironclad commitment to NATO’s Article 5,” the White House said.

Article 5 is the mutual defense clause in which every NATO country agrees to protect each other and treat an armed attack on one as an attack on all.

President Biden authorized the Department of Energy on Tuesday to release 30 million barrels from the U.S. Strategic Petroleum Reserve as part of a global effort to mitigate supply shocks from Russia’s invasion of Ukraine.

The decision is part of a broader effort by the International Energy Agency member states to collectively release an initial 60 million barrels of crude oil from their respective reserves.

“Today’s announcement is another example of partners around the world condemning Russia’s unprovoked and unjustified invasion of Ukraine and working together to address the impact of President Putin’s war of choice,” White House press secretary Jen Psaki said. “President Biden was clear from the beginning that all tools are on the table to protect American businesses and consumers, including from rising prices at the pump.”

Ms. Psaki said the member states will monitor markets and consider future releases.

“We are prepared to use every tool available to us to limit disruption to global energy supply as a result of President Putin’s actions,” she said. “We will also continue our efforts to accelerate diversification of energy supplies away from Russia and to secure the world from Moscow’s weaponization of oil and gas.”

For days, Republicans have urged Mr. Biden to tap into domestic production to help wean the world off Russian fuel, including new drilling on federal lands and the resumption of the Keystone XL Pipeline.

FRANKFURT, Germany – An Austria-based subsidiary of Russia’s state-owned Sberbank has been ruled likely to fail after depositors fled due to the impact of Russia’s invasion of Ukraine.

The European Central Bank said early Monday that the bank had 13.6 billion euros in assets at the end of last year, but has experienced “significant deposit outflows” due to “geopolitical tensions.”

The ECB says Vienna-headquartered Sberbank Europe AG “is likely to be unable to pay its debts or other liabilities as they fall due.” The bank is a fully owned subsidiary of Russia’s Sberbank, whose majority shareholder is the Russian government.

Europe’s bank resolution board separately says it has imposed a payments ban on money owed by the bank and a limit on how much depositors can withdraw. The board will decide on further steps, which could include restructuring, selling or liquidating the bank.

Sberbank Europe operates 185 branches and has more than 3,933 employees.

WARSAW | A sea of protesters gathered before the Russian Embassy in Warsaw over the weekend as anti-war demonstrations broke out in cities around the world.

The protests here have an extra edge because Poles have a front-row seat for the global drama over Russia‘s military invasion of neighboring Ukraine. In addition to a long and tortured bilateral history with Russia, Poland has taken in the bulk of what U.N. High Commissioner for Refugees Filippo Grandi said Sunday were some 368,000 people who had crossed the Ukrainian border into neighboring countries to flee the fighting.

Anti-Russian demonstrations were held in Germany, where an estimated 100,000 people marched in the streets of Berlin, the U.S., Canada, Switzerland, the Czech Republic, Italy, Japan, Taiwan, Georgia and other countries.

Despite a fierce crackdown by President Vladimir Putin‘s security forces, a database compiled by the Russian nonprofit OVD-Info said police detained nearly 2,100 participants in anti-war protests in Moscow, St. Petersburg and dozens of other cities again Sunday. More than 3,000 people already had been arrested after police and security forces moved in on demonstrations since Wednesday, when Russian forces crossed into Ukraine.

In Warsaw, the street-facing windows of the Russian Embassy were noticeably darkened as a crowd outside shouted “Ukraine without Putin” and “Ukraine is Europe” as they hoisted Polish and Ukrainian flags.

The outcry in the Polish capital has become a nightly condemnation of Russia‘s aggression and an appeal to world leaders to do more to put an end to the war.

“As a citizen of Poland and as a citizen of the European Union, I demand action from politicians and diplomats,” said Bartlomiej Jankowski, 26, a Warsaw resident who attended Saturday’s protest. “Not speeches. Not tweets. Not just talking.

“If we leave Ukraine alone, everyone is going to lose,” Mr. Jankowski said. “All of Europe. We are all going to lose this war together.”

U.S. and world leaders have stepped up financial and economic sanctions on Russia since the invasion began, and organizers of sports events including racing and soccer have either banned Russian contestants or canceled Russian events. Still, some were skeptical that those moves would force Mr. Putin to back down.

One sign waved at Saturday’s protest in Warsaw read: “Sanctions didn’t work with Hitler either.”

Other signs called for Ukraine‘s admission into NATO, a key appeal voiced by Ukrainian President Volodymyr Zelenskyy and one that Western leaders have been reluctant to support.

“I have no doubt that all people throughout Europe share the same voice in wanting to stop the war,” said one protester who wished to remain anonymous. “I cannot tell the same from our leaders.”

Nearly 20,000 protesters took to the streets in Switzerland’s capital, where the Ukrainian flag flew over the city council. In a country that has long prized its neutral status, hundreds demonstrated in front of the United Nations headquarters in Geneva.

Russia‘s ‘bloody monster’

In Russia, Sunday’s protests appeared smaller than those of the first days of the war but still presented a remarkable public challenge to Mr. Putin‘s autocratic rule.

“I have two sons, and I don’t want to give them to that bloody monster. War is a tragedy for all of us,” 48-year-old Dmitry Maltsev, who joined the rally in St. Petersburg, told The Associated Press.

In St. Petersburg, where several hundred gathered in the city center, AP reported that police in full riot gear were grabbing one protester after another and dragging some into police vans, even though the demonstration was peaceful. Footage from Moscow showed police throwing several female protesters onto the ground before dragging them away.

The Ukrainian government on Sunday took another step to encourage resistance within Russia. It launched a Russian-language website that it said Russian families could use to find soldiers who had been killed or taken prisoner in the fighting. The website displays identification documents of those killed and photos of corpses that Kyiv says are Russian soldiers killed in the invasion.

“I know that many Russians are worried about how and where their children, sons [and] husbands are and what is happening to them — so we decided to put this online so that each of you could search for your loved one who Putin sent to fight in Ukraine,” Viktor Andrusiv, an official in the Ukrainian Interior Ministry, says in a video on the website.

“If your relatives or friends are in Ukraine and participate in the war against our people — here you can get information about their fate,” the website says on its homepage.

The name of the Ukrainian website, 200rf.com, is a bit of military psychological warfare: It’s a play on the grim Soviet-era euphemism “Cargo-200,” referring to the body bags of soldiers killed in Russia‘s disastrous decade-long military campaign in Afghanistan.

Warsaw‘s Mr. Jankowski said the war is especially personal for Poles.

“It’s terrifying,” he said. “It’s not something abstract. It’s happening right here just beyond the border.”

He said he, like so many others here, has friends in Ukraine whom he speaks with daily.

“When I woke up on Thursday, the invasion happened and it was a different reality.”

Yevhenii Dacenko, a Ukrainian immigrant living in Warsaw, said the protests show an important symbol of unity between the two countries.

“Everybody stands together,” Mr. Dacenko said. “We will never surrender.”

• David R. Sands contributed to this article, which is based in part on wire service reports.

Russian President Vladimir Putin ordered Moscow’s military to raise the alert status of its large nuclear forces on Sunday, and the threat will test a 2012 agreement that calls on China to provide a nuclear deterrent umbrella for Ukraine.

Chinese President Xi Jinping and then-Ukrainian President Viktor Yanukovych signed the agreement on Dec. 5, 2012, promising that China’s nuclear forces would protect Ukraine from nuclear threats.

The bilateral treaty described the two states as “strategic partners.”

“China pledges unconditionally not to use or threaten to use nuclear weapons against the nuclear-free Ukraine and China further pledges to provide Ukraine nuclear security guarantee when Ukraine encounters an invasion involving nuclear weapons or Ukraine is under threat of a nuclear invasion,” a joint statement on the pact said.

A Chinese Embassy spokesman did not immediately return an email request for comment on whether China will invoke the agreement in providing a nuclear deterrent for Ukraine.

Nearly two decades earlier, Ukraine voluntarily gave up the nuclear weapons it inherited upon the dissolution of the Soviet Union, which would’ve been the world’s third-biggest arsenal, and joined the global treaty on the Non-Proliferation of Nuclear Weapons as a non-weapons state.

As Russian military forces bogged down in efforts to pacify Ukraine rapidly using a three-pronged military offensive, Mr. Putin said Sunday that “aggressive statements” by NATO prompted the directive.

“Western countries aren’t only taking unfriendly actions against our country in the economic sphere, but top officials from leading NATO members made aggressive statements regarding our country,” Mr. Putin said in comments broadcast on Russian television.

If the higher alert status is detected by U.S. and western intelligence agencies, U.S. strategic forces – missiles, submarines and bombers – would almost certainly respond by raising their alert status.

The nuclear alert is part of a new Russian military doctrine called “escalate to de-escalate” that reflects Moscow’s weaker conventional forces and stronger nuclear power.

U.S. defense officials have said the new doctrine means Russia’s military will more rapidly escalate to the use of nuclear weapons, tactical nuclear arms or possibly strategic weapons, in a regional conflict.

At the Pentagon, a senior defense official said the United States “had no reason to doubt” the ordering of a higher nuclear alert status.

The official said the action represented an unnecessary “escalatory” threat since Russia is not facing any nuclear dangers from NATO or the west.

“And escalatory because it is clearly potentially putting at play forces that if there’s a miscalculation could — could — make things much, much more dangerous,” the official said.

Regarding whether U.S. nuclear forces have gone on a higher alert status in response, the senior official said “we do not talk about the specifics of our strategic deterrent posture.”

“I would just tell you that we remain confident in our ability to defend ourselves and our allies, and our partners, and that includes in the strategic deterrent realm, and that is as far as I’m going to go on that question.”

The increased nuclear danger comes as the office of Ukrainian President Volodymyr Zelenskyy said talks between Ukrainian and Russian officials would take place at the Belarusian border.

China’s government has tacitly supported the Russian military operation against Ukraine by not condemning the military aggression and repeatedly announcing that Moscow had “legitimate security concerns” with Ukraine.

The Biden administration also shared U.S. intelligence with Chinese officials in the run-up the conflict in a failed bid to gain Beijing’s support for pressure on Mr. Putin not to invade Ukraine.

Instead of helping the west, China’s government shared the intelligence on Russian troop deployments with Moscow, highlighting the growing alliance between the two countries.

Ukraine developed a close arms relationship with China since it achieved independence from the Soviet Union in 1991.

China bought an unfinished aircraft carrier from Ukraine for $20 million in the 1990s and turned it into the People’s Liberation Army’s first aircraft carrier.

Ukraine also has sold jets and aircraft engines to China, and provided design information that was incorporated into Chinese Y-series military transport and surveillance aircraft.

Former State Department policy official Miles Yu, who first disclosed the China–Ukraine nuclear pact, said the nation most likely to threaten the use of nuclear weapons against Ukraine is Russia, another strategic partner of Beijing.

“In the hypothetical scenario of a Russian nuclear threat against Moscow’s former satellite Ukraine, would China keep its pledge to confront Moscow with its nuclear weapons?” Mr. Yu stated.