The U.S. has indications that four Russian cruise missiles crashed in Iran rather than Syria, suggesting there were malfunctions, Defense Secretary Ash Carter confirmed Friday.

Carter spoke at a press conference in London with British Defense Secretary Michael Fallon. It was the first public comment by a U.S. official on the cruise missile failures. The British are part of the coalition striking Islamic State fighters in Iraq, but not doing strikes in Syria.

Russia fired a total of 26 of the long-range missiles at Syrian targets. The officials said it’s unclear whether the errant missiles, launched from Russian ships in the Caspian Sea, caused any significant damage in Iran. Both the Russian government and state-run Iranian media accused the United States of inaccurate or deliberately deceptive statements

The cruise missile attack in Syria was part of an expanding Russian military campaign that began with airstrikes on Sept. 30. U.S. and NATO leaders condemned the attacks as an effort to prop up the Syrian government of Bashar Assad, rather than to target Islamic State fighters.

Russia’s use of cruise missiles has also fueled worried about mishaps in the skies over Syria and the need for Moscow to agree to certain flight safety procedures proposed by the U.S.

Carter has made it clear that the U.S.-led coalition will not agree to cooperate with Russia in the fight against the Islamic State and no collaboration is possible as long as Moscow continues to strike other targets.

The U.S. is limiting its discussions with Russia to basic, technical talks about efforts to ensure that flights over Syria are conducted safely and, “That’s it,” he has said, prompting protests from Russian leaders who want broader talks.

Carter’s stop in London is his last in a weeklong trip across Europe, meeting with defense officials in Madrid and Rome as well as attending a NATO meeting of defense ministers.

NATO talked tough Thursday about Moscow’s expanding military activity in Syria, but the U.S.-led alliance’s main response to the Russian airstrikes and cruise missile attacks was a public pledge to help reinforce the defenses of member nation Turkey if necessary.

“NATO is able and ready to defend all allies, including Turkey, against any threat,” alliance secretary-general Jens Stoltenberg said as the NATO meeting began.

The meeting was dominated by concerns about Russia’s military actions in Syria. Over the weekend, Turkey reported back-to-back violations of its airspace by Russian warplanes. And the Russian airstrikes have been also been backing Syrian government ground combat in Syria.

(AP)