Russia's military denied any involvement and US Defense Secretary James Mattis described it as "perplexing" without elaborating.
Three people inside the tank were killed by a U.S. MQ-9 Reaper drone with precision-guided munition, but no U.S troops or Syrian Democratic Forces (SDF) militants were hurt in the incident, a defense official told Fox News on Tuesday. "I think the Russians would have told us", said Mattis.
Russian Federation does not rule out that the United States intends to stay in Syria for a long time, "if not forever", he went on.
Putin, with Iran's help, turned the tide of the seven-year war by committing air- and manpower to buoy Assad's beleaguered forces in 2015, quieting USA calls for the Syrian leader's immediate removal.
Analysts have grown increasingly concerned that the conflict in Syria could spill well beyond its borders, given the number of powers engaged in the country.
On Tuesday, Bloomberg News reported that U.S. and Kurdish forces in Syria had killed 200 fighters last week, including many Russian contract soldiers, according to several Russian sources and an American official.
The US, with its advisers stationed at the base alongside Syrian Democratic Forces troops, responded with a combination of aircraft and artillery fire. There were no coalition or SDF casualties, Dillon said.
Russian forces are supporting the Syrian government in the fight against opposition groups, some of which are backed by the United States, and elements of both sides are fighting the last remnants of the Islamic State group in Syria.
Several Russians who had been hired as paramilitary contractors were among more than 100 men killed in United States airstrikes in northern Syria last week, according to their friends and families.More news: Wind alters Shiffrin's race lineup
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Russia, which along with Iran has supported the Assad regime, declined to comment on the casualties.
Without mentioning the incident directly, Russia's foreign minister, Sergey Lavrov, warned on Tuesday that "Americans have taken unsafe unilateral steps" in Syria in siding with SDF forces, who control an extensive region in northern Syria.
The U.S.is in talks with Russian Federation now in search of an explanation for what happened, said two administration officials who asked not to be identified discussing private conversations.
"Coalition officials maintained regular contact with Russian counterparts via established deconfliction lines to avoid misperceptions and miscalculations that could endanger each other's forces".
However, Harrigian refused to speculate on the composition of the hostile force.
The air force general said the United States was in contact with Russian Federation before carrying out the defensive strike. "We're dealing with an unusual situation", though it shouldn't be blown out of proportion, he said.
Russian Federation signed a "road map" agreement with Assad's government last month to assist in rebuilding the nation's electricity network. Prigozhin, who's denied any links to Wagner, was sanctioned by the U.S. Treasury in 2016, which said he has "extensive business dealings" with the Russian Defense Ministry.
Many of the Russian private fighters in Syria reportedly work for The Wagner group, founded by retired Lt. Col. Dmitry Utkin. CBS also notes the interesting fact that some Turkish forces were present at the SDF headquarters alongside the Americans, even as tensions between the US and Turkey are mounting near the Turkish border.
More than 45 Russian military personnel have been officially confirmed killed since then.