The United States will do its "very best" to keep Turkey in NATO, the U.S. national security adviser said on Sunday ahead of a White House visit by Turkish President Recep Tayyip Erdogan. 

Erdogan's scheduled meeting on Wednesday with President Donald Trump comes amid fraying relations between the two allies, aggravated by its recent offensive against U.S. Kurdish allies in Syria. 

Robert O'Brien, Trump's new national security adviser, suggested in an interview with CBS's Face the Nation that keeping Turkey in NATO was of overriding importance to the administration. 

"They play a very important role. So losing Turkey as an ally is not something that is good for Europe or for the United States. And we're going to work on making sure that we can do our very best to keep them as a NATO member," he said. 

The U.S. House of Representatives, however, voted on Tuesday to sanction Ankara for its assault last month on Kurdish-controlled territory in northern Syria. 

The same day, it approved a resolution recognizing the "Armenian genocide," in a symbolic but unprecedented rebuke to Turkey. 

The House had previously passed a resolution warning Turkey against going through with a purchase of Russian S-400 air and missile defense system, which Ankara has defiantly ignored. 

Asked whether Trump would veto the sanctions against Turkey, O'Brien said, "We have to see what happens." 

"If Turkey won't get rid of the 400, Turkey will feel the impact of those sanctions," O'Brien said. 

"There is no place in NATO for the S-400 and for Russian purchases, and that's a message that the president will deliver to him very clearly when he is here in Washington." 

(Cover: U.S. President Donald Trump with White House national security adviser Robert O'Brien in Los Angeles, California, U.S., September 18, 2019. /VCG Photo)