Staffers at the State Department have begun calling U.S. citizens still in Ukraine and urging them to leave, according to BuzzFeed News. “Just got a call from a person reading from a script reiterating the directive for Americans to leave Ukraine and asking whether I’d departed yet,” freelance photographer Pete Kiehart tweeted. “I told them I was staying as a journalist. ‘Well, be safe,’ the caller responded.” Meanwhile, the White House said Friday it believes Russia could strike within the week. The stark warning on Friday came from National Security Adviser Jake Sullivan, who said Russian forces had established a large enough presence that the situation could escalate “rapidly.” “The risk is high enough and the threat is now immediate enough that prudence demands that it is the time to leave now,” Sullivan said, according to the Associated Press. But he added that the U.S. does not know if Russia has made a decision yet on the invasion. “What we are saying is that we have a sufficient level of concern based on what we are seeing on the ground, and what our intelligence analysts have picked up, that we are sending this clear message.”