The Obama administration ordered the families of US military and diplomatic personnel to leave parts of southern Turkey on Tuesday and warned US citizens against travel to the region amid mounting security concerns.
The Pentagon said 670 dependents of US military personnel would be affected by the order to depart areas of southern Turkey, including Incirlik air base, which is used heavily in the fight against Isis militants.
The US State Department said a small number of diplomatic families would be affected but did not give numbers. The Pentagon said 100 military dependents in Ankara and Istanbul were not affected by the departure orders because of security measures in place there.
State Department spokesman John Kirby said the move had been under consideration for several weeks, and was not the result of any specific threat and had nothing to do with the visit to Washington this week by top Turkish officials.
Secretary of State John Kerry met Turkish Foreign Minister Mevlut Cavusoglu on Monday, and Turkish President Recep Tayyip Erdogan is due to attend a Nuclear Security Summit with other world leaders later in the week. Mr Kirby said Mr Kerry had discussed the security announcement with Mr Cavusoglu at their meeting on Monday.
"The decision to do this wasn't taken lightly. It was done after careful thought and consideration, and inter-agency coordination," Mr Kirby told a daily briefing at the State Department.
"The timing of it was completely considered independently of the Nuclear Security Summit and the visit here to Washington by Turkish officials," he added.
The US military's European Command said it had ordered the departure of families of personnel stationed in Adana, home of Incirlik. It said families of US military personnel also had been told to leave Izmir and Mugla provinces in southeastern Turkey.
"We understand this is disruptive to our military families, but we must keep them safe and ensure the combat effectiveness of our forces to support our strong ally Turkey in the fight against terrorism," General Philip M. Breedlove, commander of the US European Command, said in the statement.
The departures do not indicate a decision to permanently end US families' presence at military facilities in southern Turkey, the statement said.
The US State Department said it had ordered the departure of family members of government workers at the U.S. Consulate in Adana. Dependents of US government employees in Izmir and Mugla provinces were also asked to leave.
The State Department issued a statement cautioning US citizens more broadly against traveling to southeastern Turkey. It also warned of "increased threats from terrorist groups throughout Turkey."