The United States on Friday was evacuating non-essential staff from its Beirut embassy, urging Americans to avoid all travel to Lebanon and defer trips to southeastern Turkey as it mulls strikes in neighbouring 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 spokesperson Marie Harf said.
The evacuations came as 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 during an August 21 attack in a Damascus suburb.
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 to protect our employees and their families, and local employees and visitors to our facilities."
Separately, the state department said the consulate general in Adana "has been authorised to draw down its non-emergency staff and family members because of threats against US government facilities and personnel."
Lebanese authorities said, meanwhile, they had boosted security measures at foreign diplomatic missions ahead of any international military action against Syria.
Harf warned any US citizens who chose to remain in Lebanon or southeastern Turkey that they "should limit nonessential travel within the country, be aware of their surroundings whether in their residences or moving about, make their own contingency emergency plans."
The conflict in Syria has increasingly spilled over into Lebanon, which is also hosting more than 700,000 refugees - some of the two million who have fled the violence that erupted in March 2011.
Turkey is also hosting hundreds of thousands of refugees, and has witnessed attacks from the Syrian regime across its shared border.
The US warning would be reviewed, Harf said. "We will continue to assess the situation and to 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 still fresh of the deadly attack by al Qaeda linked militants on a US mission in Benghazi on September 11 last year when the ambassador, Chris Stevens, and three other US staff were killed.
An internal review blasted the state department's security arrangements at the Benghazi mission as woefully inadequate.