The US government has shot down reports that President Donald Trump acquiesced to Turkey’s request to discuss Ankara’s pending purchase of a Russian missile defense system, telling Al-Monitor that its concerns “cannot be mitigated.”

The comments come after the London-based Middle East Eye news site, citing “several Turkish officials,” reported today that Trump had overruled the State and Defense departments and agreed to create a working group on the issue in a phone call with Turkish President Recep Tayyip Erdogan earlier this week. US officials have suspended Turkey’s participation in the F-35 fighter jet program over the pending purchase, but Ankara believes it can convince them that the Russian technology isn’t a threat.

“We have been clear that purchasing the S-400 would create an unacceptable risk because its radar system could provide the Russian military sensitive information on the F-35,” Department of Defense spokesman Eric Pahon told Al-Monitor. “Those concerns cannot be mitigated. The S-400 is a system Russia built to try to shoot down aircraft like the F-35, and it is inconceivable to imagine Russia not taking advantage of the collection opportunity.”