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 US official said on Friday.
Most of those strikes targeted strongholds of the Islamic State group in Raqqa and Deir-ez-Zor, said the official, who spoke on condition of anonymity.
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.
Islamic State has claimed responsibility for bombings and shootings in Paris last Friday in which some 129 people were killed. It has also claimed that it used a bomb to bring down a Russian airliner last month. All 224 people on board were killed.
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 notices included one prior to Russian strikes on Syria on Tuesday, which a US defense official has acknowledged.
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.
The United States has said that it does not coordinate targets with Russia. An international coalition led by the United States has been conducting air strikes against Islamic State targets in Iraq and Syria.