Referring to his message to foreign banks, he added: “You need to make sure that not only are you making sure that you’re watching flows into your financial institution, but you need to also help by reminding the businesses that you support that they, too, you don’t want them to be providing material support to Russian oligarchs or Russian businesses as well.”

Russia-Ukraine War: Key Developments

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Two countries inch closer to NATO. The foreign ministers from Sweden and Finland are poised to meet with their NATO counterparts to discuss the prospect of joining the alliance. In apparent retaliation, Russia halted exports of electricity to Finland after saying that a NATO expansion would pose a threat to its own national security.

A possible spoiler? A day after President Recep Tayyip Erdogan of Turkey suggested that he would be reluctant to welcome Finland and Sweden into NATO, a spokesman for the leader said the country was not trying to block the two nations’ potential membership in the alliance, but rather ensure that all members’ security concerns are considered.

On the ground. Russia’s military offensive in eastern Ukraine remains stalled, and the Ukrainians are on the offensive around the northeastern city of Kharkiv. Ukraine’s defense minister warned that the war had entered a “new, long phase” with “extremely tough weeks” ahead.

War crime case. The Ukrainian judicial authorities began a case against a Russian soldier accused of shooting a civilian. It is the first trial involving a suspected war crime by a Russian service member; the victim was a 62-year-old man on a bicycle in a village in Ukraine’s Sumy region.

Banks and financial institutions around the world have been grappling with how to remain in compliance with the waves of new sanctions against Russia.

Citigroup, the largest U.S. bank in Russia, with about 3,000 employees there, was in “active dialogue” to sell its Russian consumer and commercial-bank businesses, Jane Fraser, its chief executive, told Bloomberg this month.

Citigroup trimmed its exposure in Russia to $7.9 billion in March, down from $9.8 billion at the end of last year, according to a filing. “This weaponization of financial services is a very, very big deal,” Ms. Fraser said at a conference this month. She said she expected global capital flows to splinter as nations developed new financial systems to avoid being too reliant on Western firms.

Foreign banks with U.S. operations can find themselves caught between conflicting demands. In some cases, U.S. sanctions have required them to cut off longtime customers. Those who resisted doing so learned how serious the authorities could be about tracking down violators and hitting them with big fines.

In 2019, for instance, the British bank Standard Chartered paid $1.1 billion to settle cases brought by the Justice Department, Treasury, New York’s state banking regulator and state prosecutors over transactions it had carried out for Cuba, Syria, Iran and Sudan in violation of U.S. sanctions. Two years earlier, Deutsche Bank paid $630 million after it was caught helping Russian investors sneak $10 billion into Western financial centers. The international giants HSBC and BNP Paribas have also paid billions in the past 10 years to settle sanctions violations cases.

Lananh Nguyen contributed reporting.