The handwriting was on the wall and now the ongoing flap between the United States and Turkey over the U.S threatening to impose sanctions on Ankara, for buying a Russian missile system, is reaching a tipping point.

Turkish President Recep Tayyip Erdogan threatened to close two strategic U.S. airbases at Incirlik and Kurecik over these sanctions. 

“If necessary, we’ll close Incirlik and also Kurecik,” Erdogan said on Sunday. “If the threat of sanctions is implemented against us, we’ll respond to them in the framework of reciprocity.”

Turkish Foreign Minister Mevlut Cavusoglu also brought up U.S. base closure last week when the threat of sanctions was brought up by Washington. He stated that the base closure would “be put on the table.”

Incirlik has been a U.S. airbase since 1955. It has been a strategic spot for the United States to project power in the region. It was a key base during the Gulf War in 1991, the Global War on Terror, the invasion of Iraq and the recent campaign against the Islamic State in the Middle East. It is also home to 50 of the B-61 nuclear gravity bombs. Kurecik is a key NATO radar base  

Members of Congress have been pushing President Trump to impose sanctions on Turkey for buying the Russian S-400 missile system. They argue that this system is incompatible with membership in NATO and is a threat to the new F-35 fighter jets, because of fears that the Russians will learn valuable information about the F-35 if the Turks use both systems at the same time. 

Because of the Turkish purchase, the United States kicked Turkey out of the F-35 program, to which it had been a partner.

This move by Erdogan is seen as purely political and a signal that Turkey will not bow to either the U.S. or NATO in matters of their defense.