State Department urges Americans to leave Belarus "immediately" as tensions rise with Russia

The State Department urged all Americans in Belarus, which borders Ukraine and Russia, to leave "immediately" on Monday night, amid "concerning Russian military activity" near the border with Ukraine.

The updated guidance, which also tells Americans not to travel to Moldova, comes after a U.S. official told CBS News that Russian units near Ukraine have moved into "attack positions" and that the U.S. believes Russia will attack Ukraine by the end of the week.

The State Department advisory warned, "Due to an increase in unusual and concerning Russian military activity near the border with Ukraine, U.S. citizens located in or considering travel to Belarus should be aware that the situation is unpredictable and there is heightened tension in the region." It's a level 4 advisory, the State Department's most severe "do not travel" warning, which indicates an increased likelihood of life-threatening risks. The advisory was already a level 4 before Monday, but the warning to leave immediately is new.