The Obama administration officially expressed it's "regret" for the attack which could be interpreted as act of war. It is the first time the coalition has targeted Syrian government forces. No ISIS soldiers were harmed in the bombing.
Update 3: Russia's foreign ministry says it has "reached the terrifying conclusion" that the US is conniving with the Islamic State. As ABC reports, Russia has called for an emergency session of the United Nations Security Council over a U.S. air raid that it says struck Syrian troops battling the Islamic State group. Spokeswoman Maria Zakharova says Moscow is demanding "full and detailed explanations about whether this was deliberate support of the Islamic State or another mistake."
Zakharova was quoted by the state news agency Tass as saying that "after today's attack on the Syrian army, we come to the terrible conclusion that the White House is defending the Islamic State."
The U.S. military says it halted an air raid against IS in eastern Syria after it was informed by Russia that it might have struck Syrian troops. If confirmed, it would be the first American strike on President Bashar Assad's forces in the five-year-old conflict. The allegations come as Moscow and Washington are already at loggerheads over a five-day-old Syrian cease-fire, with each accusing the other of failing to fully implement it.
It appears this major diplomatic scandal is only starting to play out.
Update 2: it appears that Russia is angry, and has called a UN Security Council session, while reporting that Washington never announced any plans to conduct raids in the region in question:
DEVELOPING#Moscow: #Washington didn't annouces any plans to conduct raids in #DeirEzZor.
— Barzan Sadiq (@BarzanSadiq) September 17, 2016
#Moscow: #US bombing of #Syrian army positions puts the recent agreements at stake.
— Barzan Sadiq (@BarzanSadiq) September 17, 2016