US Government temporarily suspended all visa applications by Turkish citizens at the US diplomatic missions (except those for immigrant status) and later Turkish government reciprocated by temporarily suspending all visa applications (including evisa and visa-on-arrival) for US citizens to visit Turkey.
Those visitors who already have their e-visas in hand will not be affected by this situation.
Turkish Embassy in Washington said on Oct. 8 that it suspended all non-immigrant visa services at all Turkish diplomatic facilities in the U.S. in retaliation for the latest decision by the U.S. Embassy in Ankara to suspend all non-migrant visa services at its diplomatic facilities in the country.
"Recent events have forced Turkish Government to reassess the commitment of the Government of the United States to the security of Turkish Mission facilities and personnel. In order to minimize the number of visitors to our Embassy and Consulates while this assessment proceeds, effective immediately we have suspended all non-immigrant visa service at all Turkish diplomatic facilities in the US," a statement by the Embassy read.
For further details you can have a look at: http://www.hurriyetdailynews.com/turkey-suspends-us-visa-applications-after-us-decision-to-suspend-all-non-immigrant-visa-services-120549