US President Donald Trump (R) and Turkish President Recep Tayyip Erdogan attend a joint press conference at the White House in Washington D.C. on Nov. 13, 2019. Donald Trump and Recep Tayyip Erdogan failed to reach agreement on major bilateral differences during their Wednesday's meeting at the White House. (Photo by Ting Shen/Xinhua)

Turkish President Tayyip Erdogan said on Tuesday he told US President Donald Trump during talks last week that Turkey would not give up on the Russian S-400 missile defenses it procured this year, despite protests from its NATO ally.

Ankara and Washington have been at loggerheads over Turkey's purchase of the S-400s, which Washington says are not compatible with NATO defenses and pose a threat to its F-35 stealth fighter jets.

In response, the US has suspended Turkey from the jet ­program, and warned of ­possible US sanctions over the deal.

Last week, Erdogan and Trump met at the White House to overcome mounting differences ranging from the S-400s to Syria policy. During the talks, Trump urged Erdogan to drop the S-400 systems in lieu of US Patriot systems.

However, Erdogan said he had told Trump during their talks that Turkey will not abandon the S-400s.

"We agreed to seek solutions to the S-400 issue. I explained to Trump once again how we came to the point of buying S-400s," Erdogan told party members in parliament.

"I told him that we could not give up on the S-400s and that Turkey will not turn back." 

Tensions between the NATO allies were further strained last month when Turkey launched an incursion against the Kurdish YPG militia in northeastern Syria. Ankara views the US-backed YPG as a terrorist group and has been infuriated by US support.