Defense Department officials over the weekend said there’s been no formation of a joint U.S.-Turkish study group to examine the compatibility of American F-35 fighter jets with the Russian-made S-400 missile system.

The statements from Pentagon officials — along with the White House’s National Security Council (NSC) — come after a Middle East Eye report that President Trump agreed to the concept of a study group during a phone call last week with Turkish President Recep Tayyip Erdogan. Such an agreement would’ve represented a major change in administration policy, given the longstanding position that the F-35 and S-400 systems cannot be used together due to serious security fears.

But officials say no deal was made and no study group has been set up.

“The Middle East Eye report claiming a group was established to specifically address security related to the co-location of the F-35 and S-400 is incorrect and based on rumor, not facts,” said Pentagon spokesman Eric Pahon. “We continue robust discussions and meetings with our Turkish counterparts at all levels regarding the future of our [military-to-military] relationship, however 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. Those concerns cannot be mitigated.”

NSC spokesperson Garrett Marquis also pushed back on the reports.

“We have nothing new to announce at this time. We have been clear that obtaining the S-400 would create an unacceptable risk to U.S. technology, our pilots, and our aircraft,” he said.

Administration officials and lawmakers on Capitol Hill have repeatedly warned Turkey that pursuing the S-400 would mean it will no longer have access to the F-35 program.