The United States has warned that it would impose sanctions on Turkey if it pressed ahead with the S-400 deal, but Ankara has said it would not back down and has so far dismissed the warnings, as relations between the NATO allies strained.

Speaking to reporters in Ankara before departing for the G20 summit in Japan, Erdogan said he would again discuss the issue with Trump in bilateral talks on the sidelines of the summit.

Copyright Reuters, 2019