The U.S. began evacuating its embassy in Kyiv on Saturday as intelligence sources warned a Russian invasion could begin as soon as Wednesday, Politico reports.

Per Politico, the “State Department said Saturday that almost all of its 200 staff based in Kyiv will be required to leave” but that “embassy will keep a small number of “core” diplomats in Kyiv and will maintain a small consular service in Lviv, which is further away from a potential conflict zone.”

Russia announced Saturday that it is also cutting back its diplomatic presence in Ukraine. According to The Wall Street Journal, “Russian Foreign Ministry spokeswoman Maria Zakharova said Russia had decided on a ‘certain optimization’ of staffing … because it feared ‘certain provocations by the Kyiv regime or third nations.'”

Zakharova’s attempt to portray Ukraine as the potential aggressor fit with U.S. intelligence reports that Russia could conduct a “false flag” operation — in which Russians posing as Ukrainians would launch attacks on Russian forces — ahead of its invasion.

National Security Adviser Jake Sullivan warned Friday that all American civilians should leave Ukraine “as soon as possible,” and that if they failed to do so in the next 24-48 hours, there might not be “any other opportunity to leave.”

On Jan. 22, the State Department ordered the families of U.S. Embassy personnel in Ukraine to evacuate the country.

President Biden spoke with Russian President Vladimir Putin for about an hour on Saturday. According to the official White House summary, Biden “reiterated that a further Russian invasion of Ukraine would produce widespread human suffering and diminish Russia’s standing” and said the U.S. “remains prepared to engage in diplomacy” but is “equally prepared for other scenarios.”