The Defense Department on Tuesday ordered the evacuation of hundreds of military and civilian dependents from Turkey, including Incirlik Air Base, due to increased concerns about security.

The order applies to nearly 700 spouses and children at Incirlik as well as small populations in the areas of Ismir and Mugla, defense officials said.

The order is the latest sign of heightened concern about security for Americans in Turkey, particularly the area along the Syrian border where Incirlik is located.

"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," Air Force Gen. Philip M. Breedlove, commander of U.S. European Command, said in a statement issued with the announcement Tuesday.

The total U.S. military force deployed at Incirlik has grown to nearly 2,500, up from about 1,300 last year, after the Turkish government agreed to let U.S. combat aircraft use the base as a key staging area for air strikes on Islamic State militants in Syria and Iraq.

Yet the base's prominent role in the fight against the Islamic State group also raised new security concerns.

In July, worries about extremists targeting U.S. troops and their families prompted military officials to lock down the base and prohibit the roughly 5,000 American troops, civilians and dependents from venturing out to the "American alley" outside the installation's main gate, where troops for years have patronized kabob shops, carpet salesmen and local markets.

Initially there was little worry about any immediate danger among the base's military population. In September, the Defense Department offered voluntary evacuations to the roughly 900 military dependents at Incirlik, but only about 80, or less than 10 percent, decided to leave at that time, Incirlik officials said.

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The remaining dependents today, about 670 according to a defense official, will have to leave involuntarily due to Tuesday's order.

The evacuation comes amid an uptick in violence in Turkey, including a Feb. 18 car bomb in the capital, Ankara.

On March 9, the Defense Department-run school at Incirlik was closed due to security concerns and the base imposed additional force-protection measures.

Pentagon spokesman Peter Cook said the dependents will be evacuated promptly. "This will move relatively quickly," he said Tuesday.

Cook said the decision to remove dependents from Incirlik does not amount to a permanent decision to end accompanies tours at the installation.