"Our position has been made very clear to Turkey, and we are hopeful that we can find a way to solve this tough issue," Dunford said.
Both executive and legislative branches of the US government "are going to have a hard time reconciling the presence of the S-400 and the most advanced fighters that we have — the F-35," the general stated.
"We're hopeful that we can find a way through this, but it is a tough issue," the marine general told a security forum in Washington.
The comment was made after last Thursday Turkish Defense Minister Hulusi Akar said Ankara was expecting the delivery of US-made F-35 fighter jets in November despite Washington’s criticism of the decision to buy Russian S-400 air defence systems.
At the same time, Ankara continues facing strong criticism of Washington, connected with a loan agreement for the supply of the Russian S-400 defence systems signed by the country in December 2017.
READ MORE: US Wants to 'Send Signals' to Turkey on F-35 Supplies Amid S-400 Spat — Report
Recently, Reuters reported, citing Katie Wheelbarger, acting assistant secretary of defence for international security affairs, that Washington was mulling to "send signals" to convince Ankara to ditch buying the S-400. The reported "signals" include the F-35 engine overhaul depot in Eskisehir, Turkey used in the jets' production line.