U.S. officials say hundreds of military and diplomatic family members near Incirlik air base in southern Turkey are being told they can leave the country.

This message comes as the Turks become more active in the fight against Islamic State militants and attacks are being launched increasingly from the base.

The decision affects only the families of U.S. troops at Incirlik and diplomats at the consulate in nearby Adana. Families aren't required to leave, but those who do would have their departures funded by the U.S. government. Defense Department schools will remain open for those who stay.

Officials say the State Department is issuing a travel warning for the region due to concerns about an increasing security threat.

Officials weren't authorized to discuss the matter publicly, so they spoke anonymously.