The US State Department has ordered non-emergency US personnel to leave Lebanon and also approved voluntary evacuation from southern Turkey.
The department cited current tensions in the region, but did not specifically mention Syria.
The department also warned US citizens travelling in Lebanon and Turkey to remain alert to potential danger.
It did not offer details of any threats to the US embassy in Beirut, Lebanon, or the consulate in Adana, Turkey.
Congress is debating a request by President Barack Obama to wage a military strike against Syria. The BBC reports votes are expected to be held next week in the Senate and the House of Representatives.