Turkish President Erdogan said he hopes that a Russian missile system, considered by Washington as a threat to US jets, will be delivered in July.
The United States had stated that Turkey could not have both the S-400 air defense system and the F-35 American fighter jets.
But Erdogan said Turkey would hold anyone to exclude it from the F-35 program.
Turkey, a member of NATO, is committed to buying 100 F-35s and has invested heavily in the F-35 program.
Turkish companies produce 937 aircraft parts.
Erdogan said he hoped to resolve the situation with the United States by phone diplomacy before meeting with President Trump at the end of June, Reuters reported.
Turkey is pursuing an increasingly independent defense policy and has strengthened its ties with Russia following the recent deterioration of its ties with the United States and Europe.
What did the United States say to Turkey?
Acting Secretary of Defense Patrick Shanahan wrote last week to his Turkish counterpart that the US was "disappointed" to hear that Turkish personnel was sent to Russia to train on the S-400.
Another senior US official, Ellen Lord, Undersecretary of Defense, told reporters that the United States did not want Russian technicians to access F-35 vulnerabilities.
"We do not want the F-35 to be near the S-400 for a while because of our ability to understand the F-35's profile on this particular equipment," she said.
US officials had wanted Turkey to buy its Patriot missile system instead.
Turkey has the second largest NATO army, a 29-member military alliance set up to defend against what was the Soviet Union at the time.
What is the S-400 system?
The S-400 "Triumf" is one of the most sophisticated ground-to-air missile systems in the world.
It has a range of 400 km and an integrated system S-400 can shoot down 80 targets simultaneously.
Russia claims to be able to hit air targets ranging from low-flying drones to aircraft flying at various altitudes and long-range missiles.
How does the S-400 work?
- The long-range surveillance radar tracks objects and transmits information to the vehicle command, which assesses potential targets
- The target is identified and the ordered vehicle orders a missile launch
- Launch data is sent to the best placed launcher and releases ground-to-air missiles
- The engagement radar helps guide the missiles towards the target