Turkish Presidential Spokesman Ibrahim Gulen said on Friday that he will start working with the US side on Friday to reach a settlement on the issues of the Russian S-400 system and the F-35 fighter jets which affect the relations between the two countries.

They said President Erdogan and his US counterpart Donald Trump had cost him and US national security adviser Robert O'Brien to coordinate the issue.

He was speaking during a program on Turkey's state-run TRT news channel to evaluate President Recep Tayyip Erdogan's visit to the United States on Tuesday and Wednesday.

"The two presidents charged us and O'Brien during the meeting at the White House," he said.

They said the work would be done bilaterally between the two countries, not in coordination with NATO, adding that the S-400 could be used independently without being integrated into NATO's defense system.

He pointed out that the Turkish delegation went to Washington with a clear vision, and presented the theses of Turkey very openly, and that the meeting between the two presidents addressed important issues, including the safe area in Syria.

They said Trump had asked Erdogan in detail about the number of refugees in Turkey who could return and where they would return, and said that Europe should help Ankara, not enough.

He explained that President Erdogan will raise this issue at the NATO summit next month, adding that the transfer of this key idea to the NATO summit after understanding with Trump is an important outcome of this visit.

Despite what he described as gains and good results of the meeting, the Turkish presidential spokesman stressed that not all problems have been solved, considering that the current stage in the relationship between the two countries should be managed well.