Russia has given the United States advance notice before it conducted air strikes in Syria at least three times since last week's attacks in Paris, a U.S. official said on Friday.
The most recent of those strikes was conducted on Thursday by two TU-160 Blackjack bombers flying from Olenegorsk air base near the Russian border with Finland, according to the official.
Russia has also given the United States advance notice in the past week of actions involving cruise missiles and long-range bombers that crossed Iranian and Iraqi airspace into Syria, the official said.
The United States and Russia agreed to air safety protocols in October, including a ground communications link between the two sides in the event air communications failed.
Colonel Patrick Ryder, a spokesman for U.S. Central Command, said on Friday that more Russian bombs were now targeting Islamic State, which is also known as ISIS and ISIL.