The secret deal between Moscow and Washington aimed at preventing aerial accidents calls for U.S. and Russian pilots to avoid targeting or shooting at aircraft engaged in military strikes, according to defense officials.
Pentagon spokesman Peter Cook told reporters Tuesday that details of the agreement, reached this week, are being kept secret at the request of the Russians.
According to other defense officials, the accord states that aircraft, including both jets and unmanned drone aircraft, will not illuminate aircraft from other countries with targeting radar or fire upon them.
Also, the agreement bans aerobatic maneuvers, such as barrel rolls, or what pilots call "thumps"—close passes by aircraft that involve gunning engines and causing target aircraft to be shaken by jet wash.
The agreement also covers any other unsafe aerial encounters, the officials said.
In addition to U.S. aircraft, coalition nations that are conducting airstrikes and will be covered by the accord include Australia, Canada, Denmark (which suspended operations in August), France, Jordan, the Netherlands, and Britain.
The agreement also sets up a communications mechanism on the ground that will permit officials in U.S. and Russian operations centers to talk, should other electronic communications prove insufficient.
Since Russian jets began conducting bombing missions in Syria, mainly against Syrian rebels and in support of the military forces of the Bashar al-Assad regime in Damascus, there have been what Cook said were "a handful" of unsafe aerial encounters between Russian and U.S. aircraft, involving both piloted jets and unmanned drones.
In one case, a Russian jet came with 1,500 feet of U.S. aircraft in an unprofessional encounter. Russian jets have also flown close to U.S. Predator drones engaged in surveillance missions.
Cook, the Pentagon spokesman, said the memorandum of understanding (MOU) covering what the military calls the "deconfliction" of air operations, was not intended to legitimize Russia’s military operations in support of the Assad regime.
"The MOU does not establish zones of cooperation, intelligence sharing, or any sharing of target information in Syria," Cook said. "The discussions through which this MOU has developed do not constitute U.S. cooperation or support for Russia's policy or actions in Syria. In fact, far from it, we continue to believe that Russia's strategy in Syria is counterproductive and their support for the Assad regime will only make Syria's civil war worse."
In Moscow, however, Russian Deputy Defense Minister Anatoly Antonov said the memorandum was an important step toward joint cooperation between the two militaries against what he said were terrorist elements, the Associated Press reported.
"The memorandum contains a complex of rules and restrictions aimed at preventing incidents between Russian and U.S. aircraft," Antonov said.
The communications between the two militaries will include 24-hour channels and "mutual assistance in crisis situations."
"The Americans have promised to get the agreed rules to all participants of the anti-[Islamic State] coalition they lead, so that their pilots proceed from those agreements," Antonov said.
According to the Russian official, the memorandum promises "a big potential for cooperation between Russia and the U.S., including in the fight against terrorism, which we are ready to expand and deepen."
On Capitol Hill, Senate Armed Services Committee Chairman Sen. John McCain (R., Ariz.) harshly criticized the agreement, calling it "immoral."
"This ‘de-confliction’ agreement with Russia means that the United States will now be watching and moving out of the way while Russian aircraft, together with Syrian, Iranian, and Hezbollah ground forces, attack and kill brave young Syrians, many of whom our country has supported and encouraged to fight back against a brutal dictator who has slaughtered nearly 250,000 Syrians and driven half the population from their homes," McCain said.
"This is not only self-defeating and harmful to our national interests; it is immoral."
McCain said Syrian rebels had placed their trust in the United States in hopes U.S. backing would help them succeed in the civil war.
"Now we are breaking those promises in our haste to give [Russian President] Vladimir Putin clearer skies from which to bomb our partners," he said.
Russia began airstrikes in Syria on Sept. 30 using jet fighters and attack helicopters. It then launched a series of long-range cruise missile strikes, firing 26 SS-N-30 Kalibr missiles from ships in the Caspian Sea.
Russian military intervention in Syria followed Moscow’s complaints that U.S. military efforts to stop the Islamic State in Syria and Iraq were failing to stem the terrorist group’s advance.
Marine Corps Gen. Joseph Dunford, chairman of the Joint Chiefs of Staff, said in Iraq that he has secured assurances from the Iraqi government that Baghdad will not seek Russian airstrikes against Islamic State-controlled regions of that country.
"I said it would make it very difficult for us to be able to provide the kind of support that you need if the Russians were here conducting operations as well," Dunford told reporters, according to a Reuters account.
"Both the minister of defense and the prime minister said: ‘Absolutely.' There is no request right now for the Russians to support them, there's no consideration for the Russians to support them, and the Russians haven't asked them to come in and conduct operations."
Dunford said the air safety accord will permit the U.S. and allied forces to continue airstrikes.
"I’m not going to tell you there's not going to be friction," Dunford said, noting possible course changes for U.S. jets in response to Russian flights.
"What I'm telling you is the basic execution of the plan is going to continue."