Russian cruise missiles aimed at targets in Syria crashed in rural Iran, U.S. officials told the New York Times Thursday.

Defense Secretary Ash Carter said Russia fired the missiles without any advance notice and criticized the action as being “unprofessional,” the Times reports. It has not yet been revealed where exactly the missiles landed or whether there were any casualties.

At a NATO news conference in Brussels, Carter said that ““in coming days, the Russians will begin to suffer casualties.”

According to the New York Times, this was the first time these cruise missiles had been fired during wartime.

[NYT]

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Write to Tessa Berenson at tessa.berenson@time.com.