ANKARA, Dec. 11 (Xinhua) -- Turkey will retaliate if the United States takes steps against it, Turkish Foreign Minister Mevlut Cavusoglu said on Wednesday, referring to a possible move by Washington to impose sanctions over Turkey's purchase of Russian S-400 defense systems.

"Members of the U.S. Congress need to understand that they cannot achieve anything by imposition," he said in a televised interview with the A News Channel.

Asked if Turkey will respond, the minister said Ankara will assess the steps it will take in the case of the worst scenario, including the halting of the use of the Incirlik Air Base in southern Turkey and Kurecik radar system of NATO.

He stressed Turkey attaches importance, not to the decision of the U.S. Congress, but to the U.S. administration.

Cavusoglu also said Ankara was open to alternatives to F-35 jets if the U.S. insists on not delivering the aircraft and Turkey will evaluate alternatives including Russian warplanes.

Turkey and Britain have agreed to speed up work on a project to build fighter jets, he added.