Turkey has responded with anger and threats after a US Congressional panel passed a resolution calling the massacre of Armenians at the hands of the Ottoman Empire genocide.
Ankara Thursday recalled its ambassador in Washington for consultations.
Hundreds of Turks marched in the streets of Istanbul, saying Turkey would never allow a genocide.
Turkish President Abdullah Gul called the resolution unacceptable and accused US lawmakers of playing petty politics.
Turkish politicians say the resolution could badly damage US - Turkish relations. A
senior member of the ruling Justice and Development Party, Egemen Bagis, asked a Washington audience Thursday to imagine Turkey denying US planes permission to use Turkish airspace.
Turkey is a vital route for fuel and supplies for US forces fighting in Iraq and Afghanistan.
The White House opposes the resolution. It calls the Armenian deaths horrific, but says declaring it genocide could gravely harm US national security.
A House panel voted in favor of the resolution Wednesday 27 to 21. Speaker Nancy Pelosi says the measure will go to the entire House of Representatives for a full vote.
Armenians accuse Ottoman Turks of killing one-point-five Armenians from 1915 to 1923 to drive them out of eastern Turkey. Turkey acknowledges there was killing, but denies a genocide. It calls the death toll exaggerated and says the Armenians died in civil unrest during the collapse of the Ottoman Empire.