Russian President Vladimir Putin is the latest target of sanctions over the invasion of Ukraine, with the United States, Canada and European allies announcing they are adding direct measures against him and his foreign minister. Russia on Saturday warned it could react by opting out of its last remaining nuclear arms pact and cutting diplomatic ties.

With Russian forces on the outskirts of Ukraine's capital, diplomatic appeals appeared to come second to imposing financial pain on Russia as global condemnation — and frustration — grew.

"This war will last, and all the crises that go with it will have durable consequences," French President Emmanuel Macron said.

Acknowledging the same, the Biden administration in the U.S. said it was sending Ukraine up to $350 million US in arms and other defensive supplies from U.S. Department of Defence stockpiles, with another $250 million in defensive support possible. The Czech Republic also approved a plan to send more arms to Ukraine.

White House press secretary Jen Psaki on Friday said the U.S. was preparing individual sanctions on Putin and Foreign Minister Sergei Lavrov, likely to include travel bans. The announcement came after the European Union announced it intended to freeze Putin's assets, and British Prime Minister Boris Johnson told NATO leaders his country, too, would sanction Putin and Lavrov.

Psaki said President Joe Biden hadn't planned any more direct diplomatic overtures toward Putin, but "it does not mean we have ruled out diplomacy forever."

She said the U.S. would also sanction the Russian Direct Investment Fund, which functions as a sovereign wealth fund meant to draw capital into the Russian economy.