U.S. military families have been ordered to evacuate bases in Turkey to keep to them safe from possible attacks, officials announced Tuesday.

Pentagon Press Secretary Peter Cook said the order to leave Turkey would affect about 670 of the total of 770 dependents in the country.

The 670 dependents are at the main Incirlik airbase and two other smaller bases at Izmir and Mugla, Cook said. The approximately 100 dependents who are being allowed to stay were with spouses assigned to Ankara, the Turkish capital, and Istanbul, which were considered safer postings, Cook said.

Cook did not give a timeline for when the dependents would leave but said "my understanding is that this will move very quickly."

The departures were not a response to the Brussels terror attacks last week in which an Air Force officer and four members of his family were wounded in the explosion at the Zaventem international airport, Cook said. "I don't believe this was specifically triggered by the Brussels attacks," Cook said.

"It's not because of any one action or specific threat," Cook said, but was instead a step taken "out of an abundance of caution."

The evacuation "is intended to mitigate the risk to DoD elements and personnel, including family members, while ensuring the combat effectiveness of U.S. forces and our mission support to operations in Turkey," U.S. European Command posted in a message on its Facebook page.

The evacuation order applies to all Defense Department dependents in the Adena area, including Incirlik Air Base, Ismir and Mugla.

"The decision to move our families and civilians was made in consultation with the Government of Turkey, our State Department, and our Secretary of Defense," Air Force Gen. Philip M. Breedlove, head of the command, said in the statement.

"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," he added.

Families at Incirlik Air Base had been previously offered voluntary relocation back to the States, though most had not accepted it. Turkey has also been subject to a travel ban for service members not on official business and civilians on Pentagon accompanied orders since last year.

A military family member stationed Incirlik Air Base, who asked that her name not be used, told Military.com that official information about the evacuation is still trickling in. Her husband will continue to be stationed at the base without them for the remainder of his two-year tour, she said.

"I’m heartbroken," she said. "We're looking at basically a 15-month deployment now."

The spouse was spending spring break with her three children in Europe when the evacuation was announced and is now at Ramstein Air Base in Germany. She said families visiting there from Turkey are not allowed to return to retrieve belongings. She said about eight families were pulled from a flight to Turkey this afternoon.

The spouse said officials are allowing families with school-aged children to stay in Europe for the rest of the school year. After that, she does not yet know what they will do, she said.

She said everyone she knows at Incirlik felt safe on base.

"Several of us have joked that if they tell us to leave, we're going to hide out or chain ourselves to a tree to avoid being forced to go," she said.

Moving also brings with it a financial impact for many families, the woman said.

"Many spouses have jobs there and it's just regular life," she said. "Luckily I telecommute to a department in the states but others are rightfully nervous about the financial impact of an ordered departure on their families."

-- Amy Bushatz can be reached at amy.bushatz@military.com

-- Richard Sisk can be reached at richard.sisk@military.com