The United States evacuated non-essential staff from its Beirut embassy Friday and urged Americans not to travel to Lebanon or southern Turkey, as Washington considers strikes against neighboring Syria.
"The Department of State has ordered a drawdown of non-emergency US government personnel and family members in Beirut, Lebanon and approved the drawdown of non-emergency personnel and family members who wish to leave Adana, Turkey," deputy State Department spokeswoman Marie Harf said.
The evacuations came as the United States has been trying to build support for US military strikes on the Syrian regime in retaliation for its alleged use of chemical weapons in an August 21 attack on Damascus suburbs.
The decision had been made due to "current tensions in the region, as well as potential threats to US government facilities and personnel," Harf said in a statement.
But she stressed the State Department was acting out of "an abundance of caution."
US President Barack Obama and his administration are pressuring US lawmakers to approve limited military strikes on Syria, while at the same time seeking to build an international coalition in support of action.
It remains unclear when or if any strikes would come, but the threat has sent tensions soaring in an already volatile region.
At a press conference in St Petersburg Friday after a summit of G20 leaders, Obama refused to answer whether he would go ahead with strikes if Congress votes against military action, saying he "would not engage in parlor games."
But he insisted he was elected to make the right decisions for America's national security.
Making a parallel with World War II, Obama said: "When London was getting bombed, it was profoundly unpopular both in Congress and around the country to help the British. It doesn't mean it wasn't the right thing to do."
Lebanese authorities said they were already boosting security measures at foreign diplomatic missions ahead of any international military action.
Lebanon's security council met "in light of the tensions resulting from preparations for potential military action and the regional and international responses that could follow," the presidency said in a statement.
Harf warned any US citizens who chose to remain in Lebanon or southern Turkey that they "should limit non-essential travel within the country, be aware of their surroundings whether in their residences or moving about, make their own contingency emergency plans."
Separately, the State Department said the consulate general in Adana, a major commercial and agricultural hub, "has been authorized to draw down its non-emergency staff and family members because of threats against US government facilities and personnel."
The conflict in Syria has threatened to spill over into Lebanon and Turkey, both of which are hosting some of the two million refugees who have fled the civil war that erupted in March 2011.
The US warning would be reviewed, Harf said, adding that the US would "adjust our security posture accordingly."
The Beirut evacuation comes a month after a number of US embassies in the Middle East and Africa were closed for about a week due to an Al-Qaeda security alert.
Memories are also still fresh of the deadly attack by Al-Qaeda linked militants on a US mission in Benghazi, Libya, on September 11 last year when the ambassador, Chris Stevens, and three other US staff were killed.
And the moves for strikes on Syria have raised the prospect of more anti-US regional repercussions, including by Lebanon's Shiite Hezbollah movement, which is allied with Syrian President Bashar al-Assad.
"The potential in Lebanon for a spontaneous upsurge in violence remains. Lebanese government authorities are not able to guarantee protection for citizens or visitors to the country should violence erupt suddenly," the State Department said.
Washington's Beirut embassy was the scene of a deadly suicide bombing in 1983 that killed 63 people mostly embassy staff, CIA agents, soldiers and Marines, in what was then the worst attack ever on a US mission.