Russia has warned that it will consider U.S.-led coalition aircraft in Syria "aerial targets" after a U.S. fighter jet shot down a Syrian Air Force plane.
The threat from the Russian Defense Ministry, issued on June 19, stopped short of saying U.S. or other allied jets would be shot down but still represented a sharp increase in tensions.
The U.S.-led coalition said earlier that pro-government militiamen attacked units of U.S. partner forces known as the Syrian Democratic Forces (SDF). It said the Syrian aircraft had dropped bombs on SDF positions and was shot down near Tabqa in the afternoon of June 18 "in accordance with rules of engagement and in collective self-defense of coalition-partnered forces.”
The coalition said it contacted Russian counterparts via a special telephone line "to deescalate the situation and stop the firing."
"The coalition does not seek to fight Syrian regime, Russian, or pro-regime forces partnered with them, but will not hesitate to defend coalition or partner forces from any threat," the statement said.
The Pentagon said that the Syrian fighter bomber was engaged by a U.S. F-18 Super Hornet jet.
The Russian ministry, however, denied that the United States had used the channel before the Syrian Su-22 bomber was downed. It said it was also suspending interaction with the United States on preventing air incidents over Syria.
"Any flying objects, including planes and drones of the international coalition, discovered west of the Euphrates River will be tracked as aerial targets by Russia's air defenses on and above ground," the Defense Ministry said in its statement.
Russia is a key ally of Syrian President Bashar al-Assad.
A Syrian Army statement said the "flagrant attack” was aimed at undermining “the efforts of the army as the only effective force capable with its allies...in fighting terrorism across its territory."
"This comes at a time when the Syrian Army and its allies were making clear advances in fighting the [IS] terrorist group," it said, adding that the pilot was missing.
Meanwhile, Russian news agencies quoted Russian Foreign Minister Sergei Lavrov as saying on June 19 that the United States should respect Syria's territorial integrity and refrain from unilateral actions in this country.
"As for what is happening 'on the ground' in Syria, we proceed from the assumption that it is necessary to fully respect the sovereignty and territorial integrity in Syria," Lavrov was quoted as saying. "Therefore, any actions 'on the ground,' and there are many participants there, including those who carry out military operations, should be coordinated with Damascus."
Lavrov's deputy, Sergei Ryabkov, described the U.S. strike as another step toward "dangerous escalation."
"We are warning Washington against using similar methods in the future," Ryabkov was quoted by Interfax news agency as saying.
He added that he will meet with U.S. Undersecretary of State Thomas Shannon on June 23 in St. Petersburg to discuss problems in bilateral ties, the news agency reported.
The U.S.-backed SDF fighters are in the process of encircling Raqqa, the Islamic State militant's final major stronghold in Syria.
The Syrian Army has also taken territory from retreating IS in the area as the multifaceted battle in Syria rages on after six years.
The United States and Turkey support differing rebel groups against IS and pro-government forces, while Russia and Iran back Assad’s government.
On June 19, the Kazakh Foreign Ministry said that the next round of Syria peace talks in Kazakhstan's capital, Astana, has been scheduled for July 4-5.
At the end of the previous round of talks in Astana last month, Russia, Turkey, and Iran signed a memorandum calling for the establishment of safe zones in Syria, but some Syrian opposition representatives walked out in protest.
The six-year Syrian conflict has left hundreds of thousands dead and driven more than 11 million people from their homes.
IS fighters are also under pressure in Iraq. On June 18, Iraqi security forces launched an operation to fully liberate Mosul, the country's second-largest city.
U.S. officials said coalition forces had breached the Old City, where the final IS extremists are clinging to their last positions, using more than 100,000 civilians as human shields.