The State Department and Pentagon are ordering the families of U.S. diplomats and military personnel to leave posts in southern Turkey due to security fears.

The two agencies said dependents of American staffers at the U.S. consulate in Adana and the Incirlik air base and two other locations must leave. The so-called "ordered departure" notice means the relocation costs will be covered by the government.

The move comes amid heightened security concerns throughout Turkey and was accompanied by an updated travel warning advising U.S. citizens of an increased threat of terrorist attacks.

It also comes as Turkey's president is set to arrive in Washington to attend President Barack Obama's nuclear security summit.