The U.S. and Russia went to war over Syria on Wednesday. Luckily, the U.S. and its allies confined their bombing runs to the northern part of the war-torn nation, against targets belonging to the Islamic State of Iraq and Greater Syria. Russia, although it says it has been dispatching warplanes to help fight ISIS, apparently confined its initial attacks Wednesday to Syria’s west, targeting non-ISIS rebels trying to overthrow Syrian President Bashar Assad.

Russia’s bold move is designed to protect Assad, embarrass the U.S. and enhance Moscow’s role as a global actor. It’s a roll of the dice by Russian President Vladimir Putin, and is likely to tighten Assad’s hold on power, at least temporarily, U.S. officials say. But its contradictory stated goals—to support Assad while fighting ISIS—is like “pouring gasoline on the fire,” Defense Secretary Ashton Carter warned. U.S.-led air operations over Syria will continue, he added.

“This is a way for Putin to embarrass us and keep Assad propped up,” says Anthony Zinni, a former Marine four-star general and chief of U.S. Central Command. “As long Putin helps Assad stay in power, it makes us look bad, so it’s a net gain for Putin.”

Senator John McCain, R-Ariz., chairman of the armed services committee, blamed Obama’s arm’s-length handing of the four-year-old Syrian civil war for creating a situation “for a Russian autocrat to join with an Iranian theocrat to prop up a Syrian dictator.” He said it was the result of “a total lack of American leadership.” Syria is a long-time ally of both Moscow and Tehran.

The sudden Russian attacks caught U.S. officials by surprise. On Tuesday, the Pentagon said Washington and Moscow soon would begin discussing “deconfliction” to ensure neither side’s warplanes tangled with the other’s. But only hours later, a Russian military officer arrived at the U.S. Embassy in Baghdad to warn that his air force would launch bombing missions over Syria in an hour. The strikes came after the Russian parliament’s upper house voted 162-to-0 to authorize military action in Syria.

“This is not the kind of behavior that we should expect professionally from the Russian military,” Carter said. But Zinni, who ran U.S. Central Command from 1997 to 2000, isn’t surprised by the short notice given by the Russians for the first of their bombing runs. “The Russians are doing what we would probably do,” he says. “I’m sure this sort of deconfliction is what you’re going to see from both sides—very short notice, ‘stay out of this airspace,’ and that’s it.”

Russian officials said their targets included ISIS military vehicles and supplies. U.S. officials disputed that, saying the targets of the attacks around the Syrian city of Homs are locations where ISIS isn’t operating. Secretary of State John Kerry told the UN that the U.S. would have “grave concerns” if Russia struck rebel groups, other than ISIS or al Qaeda, battling Assad (there are 1,200 different rebel groups inside Syria).

Early reports from Homs province said at least 37 civilians had been killed in the Russian strikes. “You can expect to see greater numbers of collateral civilian casualties by Russian air strikes than by the U.S. led anti-Islamic State coalition,” warns Dave Deptula, a retired Air Force lieutenant general who ran the air war over Afghanistan in the months after 9/11. “The current U.S. policy does not allow air strikes without near-certainty of avoidance of collateral civilian casualties—the Russians will not be so careful.”

“Putin is prepared to use military force whenever and wherever he thinks it suits Russian interests,” says Charles Dunlap Jr., a former deputy judge advocate general of the U.S. Air Force and now a law professor at Duke University. “This message will not be lost on Russia’s nervous neighbors in Europe and elsewhere.” But Arab nations, led by Saudi Arabia, have made clear that they will not cooperate with Russia and will respond by bolstering their aid to the rebels fighting Assad.

Chances of clashes between U.S. and Russian warplanes over Syria are slim, but real. “With each side seeming to have its own military objectives and corresponding target sets, the risk of inadvertent conflict is particularly high,” says retired general Merrill McPeak, one-time fighter pilot and former Air Force chief of staff. “Armed aircraft passing each other in such confined airspace will find it pretty easy to feel threatened.”

Both sides fear that their pilots could be shot down and taken prisoner. In February, ISIS burned a captured Jordanian F-16 pilot to death after his plane went down inside Islamic State territory. “If a Russian aviator falls into the hands of ISIS, and is burned alive like the Jordanian pilot, I would expect an extremely violent Russian response,” Dunlap says. The U.S. is taking steps to minimize the chances of that happening. On Tuesday, the Air Force said the U.S. has moved combat search-and-rescue helicopters to the southeastern Turkish city of Diyarbakir to make it easier to rescue any downed allied pilot. “I hope we have considered what we will say and do if one of our aircraft is lost,” McPeak says. “If I was running air ops on our side, I’d make sure my mistakes made the situation more dangerous for [the Russians] than it will be for us.”

Fear of such losses motivates both U.S. and Russian leaders. Like Obama, Russian President Vladimir Putin has repeatedly said Russian ground troops will not be dispatched to Syria to fight the rebels. He’s old enough to remember the 1979-1989 Soviet occupation of Afghanistan, which led to the deaths of 15,000 Soviet troops and helped lead to the collapse of the Soviet Union two years later.

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