The Pentagon rejected an offer by Poland to send its fleet of MiG-29 fighter jets to Ukraine using a U.S. airbase in Germany, saying it “raises serious concerns for the entire NATO alliance.” This comes as Vice President Kamala Harris embarks on a two-day visit to Poland and Romania. Meanwhile, efforts are ramping up to further isolate Russia. On Tuesday, President Biden announced the U.S. is banning Russian oil.

President Joe Biden: “Russian oil will no longer be acceptable at U.S. ports, and the American people will deal another powerful blow to Putin’s war machine. This is a move that has strong bipartisan support in Congress and, I believe, in the country. Americans have rallied support — have rallied to support the Ukrainian people and made it clear we will not be part of subsidizing Putin’s war.”

In response, the Kremlin accused the U.S. of declaring an economic war on Russia. The U.S. imports 3% of its crude oil from Russia. British Prime Minister Boris Johnson announced the U.K. will phase out Russian oil imports by the end of the year. Meanwhile, the European Union outlined plans to cut Russian gas imports by two-thirds this year and end dependency on Russian fossil fuels “well before 2030.” McDonald’s, Coca-Cola, Pepsi and Starbucks have temporarily stopped doing business in Russia.

Ukraine’s state-run nuclear company is warning of a radioactive leak risk after losing power at the Russian-occupied Chernobyl plant. Meanwhile, a Moldovan oil tanker appears to still be burning in the Black Sea, nearly two weeks after it was reportedly hit by a Russian military strike.