Jake Sullivan, the national security adviser, warned that President Vladimir V. Putin of Russia could launch a major assault on Ukraine before the end of the Winter Olympics in Beijing, but said that Mr. Putin had not reached a final decision yet.
“We are in the window when an invasion could begin at any time should Vladimir Putin decide to order it. I will not comment on the details of our intelligence information, but I do want to be clear: It could begin during the Olympics. We encourage all American citizens who remain in Ukraine to depart immediately. We want to be crystal clear on this point. Any American in Ukraine should leave as soon as possible and in any event, in the next 24 to…
