WASHINGTON, Dec. 5 (Xinhua) -- U.S. Secretary of Defense Mark Esper said Thursday there had been "no movement" with regard to getting Turkey to abandon the Russian S-400 missile system.

"We are where we are, there is no movement at this point," Esper told Reuters in an interview, adding "where they are going with S-400s is the wrong direction."

The remarks were made after the Dec. 3-4 North Atlantic Treaty Organization (NATO) summit held in London, where Esper took part in meetings with the Turkish side.

During the summit, U.S. President Donald Trump said the two sides remained in talks on the issue, noting that prior to Ankara's decision to purchase the S-400 missile system, it was denied the opportunity to buy the U.S. Patriot missile system.

The S-400 missile system has been a major thorn in the U.S.-Turkey relationship after Turkey signed a 2.5 billion U.S. dollar agreement with Russia to purchase S-400 missile batteries in 2017, and began taking deliveries in July this year.

In response, Washington removed Ankara from its F-35 fighter jet program, in which Turkey is a buyer and manufacturer, for fear that the Turkish move might enable Russia to obtain sensitive information on the aircraft.

Earlier this month, two U.S. Senators issued a letter urging sanctions against Turkey in a move less than a month after the November visit by Turkish President Recep Tayyip Erdogan to the White House.