Monitoring by U.S. military and intelligence assets has concluded that at least four missiles crashed as they flew over Iran. One official said there may be casualties, but another official said this is not yet known.
It's unclear where in Iran the missiles landed. The Russian ships have been positioned in the south Caspian Sea, meaning the likely flight path for missiles into Syria would cross over both Iran and Iraq.
The Russians have been firing a relatively new cruise missile called "Kaliber," using it for the first time in combat.