The diplomatic mission explained this by “arbitrary reading of laws, the risk of detention,” as well as “we are building up Russian military power, causing concern” near the Belarusian-Ukrainian border.
The embassy invites US citizens to leave Belarus "by commercial or private means", - according to the State Department website.
Earlier, the State Department had already warned Americans against entering Moldova. In addition, he asked fellow citizens to leave the territory of Transnistria.
It's worth reminding that the United States has recently been stubbornly declaring that Russia is allegedly preparing an "invasion" on the territory of Ukraine. Moscow denies these reports. For example, on February 11, Washington indicated that Russia would attack Ukraine before the end of the Beijing Olympics, presumably on February 15 or 16. The EU and the UK doubt it.
Foreign Minister Sergei Lavrov, during a telephone conversation with US Secretary of State Anthony Blinken, called the statement about the planned "invasion" of Ukraine a provocation.