WASHINGTON — America's top uniformed official said lines of communication remain open with Russia following the shootdown of a Syrian regime jet by an American aircraft.

The situation in Syria escalated Sunday when a U.S. Navy F/A-18 Super Hornet shot down a Syrian regime Su-22 fighter — the first time a U.S. plane shot down a manned aircraft since 1999. The Russian Ministry of Defense claimed in a statement that the pilot ejected over territory controlled by ISIS and that his "fate is unknown."

In response, Russia announced Monday that any aircraft that fly west of the Euphrates River will be "tracked" by anti-aircraft systems and that it was halting the use of a military deconfliction line, set up to make sure U.S. and Russian forces did not target each other during the conflict. That includes both manned and unmanned aircraft used by the anti-Assad coalition, including American jets, raising the fear that U.S. forces could be shot down by Russian systems.

Gen. Joe Dunford, chairman of the Joint Chiefs of Staff, did not address the reports from Moscow that Russian weapons may track allied planes, instead calling for calm by saying, "The worst thing any of us could do now is address this thing with hyperbole."

As to the deconfliction line being shut down, Dunford told an audience at the National Press Club, "That link is still ongoing here this morning. We’ve still been communicating over the last few hours," but added, "I would just tell you we’ll work diplomatically and militarily in the coming hours to reestablish deconfliction" between Russia and the U.S.

A clarification about whether the deconfliction line remains specifically open was not immediately available, but last week, Dunford said there are three ways the Pentagon can contact their Russian counterparts.

"We have a direct communication between our air operations center and the Russians on the ground in Syria. We have a three-star channel, it's on the joint staff, it's my J5 that communicates with his counterpart in the Russian general staff. And then I speak routinely to the chief of Defense, General Gerasimov," Dunford told the Senate Armed Services Committee June 13.

However, Dunford said Monday that he had not talked to his Russian counterpart since Sunday’s incident.

Asked about the legal justification for the U.S. to shoot down a Syrian government jet, Dunford said the 2001 Authorization for the Use of Military Force (AUMF) covers American forces, because they are targeting ISIS on the ground in Syria.

The general added that he would welcome a new AUMF from Congress, which he said would be "very positive" for American troops.

Aaron Mehta was deputy editor and senior Pentagon correspondent for Defense News, covering policy, strategy and acquisition at the highest levels of the Defense Department and its international partners.

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