Russia continues the attack, again stopping the evacuation of the Ukrainian port city

Mr. Blinken also confirmed reports that the United States is in discussions with Poland to supply Soviet-era fighter jets to Ukraine, with US F-16s flying to Poland to replace them, following Mr. Zelenskiy’s requests for aircraft that Ukrainian pilots know how to fly.

“Now we are actively considering the issue of aircraft that Poland can provide to Ukraine, and we are looking at how we could replenish stocks if Poland decides to supply these aircraft,” Mr. Blinken said. “I can’t speak to the timeline, but I can just say that we’re very, very actively looking at it.”

But Polish officials seemed less than enthusiastic. After President Andrzej Duda said last week that Poland would not supply the planes, Prime Minister Mateusz Morawiecki’s office tweeted Sunday: “Poland will not send its fighter jets to Ukraine nor allow the use of its airports. We help a lot in many areas.”

And Moscow has warned against the idea, threatening countries that allow the Ukrainian military to use their airfields.

Over the past week, the United States, Europe and other countries have frozen hundreds of billions of dollars worth of Russian assets, excluded Russian banks from the system that allows cross-border payments, and erected steep barriers to investment in Russia. Businesses are leaving at an ever-increasing rate, the Moscow stock market has yet to open, the ruble has plummeted, and residents face the prospect of severe shortages. On Sunday, credit card company American Express suspended operations in Russia, a day after Visa and Mastercard did the same.

In Russia, crackdowns on independent media continued after BBC World News was taken off the air and Radio Free Europe/Radio Liberty, a US-funded media outlet founded during the Cold War, announced it would cease operations in the country.

But thousands of Russians defied police and rallied across the country on Sunday against the war in Ukraine, despite the threat of lengthy prison terms. Human rights group OVD-Info said at least 1,950 people were arrested in 44 cities on Sunday, bringing the total number of Russians arrested for anti-war protests since Feb. 24 to over 10,000.