For months the U.S watched uneasily as Russia built up its military presence in Syria with shipments of sophisticated weaponry and military aircraft. Russian President Vladimir Putin insisted that his main goal in Syria was to defeat the Islamic State, not prop up the beleaguered regime of Syrian President Bashar Assad. He even invited the U.S. to coordinate the two countries' airstrikes against ISIS, a proposal White House officials apparently were seriously considering as recently as a week ago. But then came Russia's opening salvo against all of Mr. Assad's opponents except for the Islamic State, and the White House realized that once again it had been duped. Now it finds itself scrambling to figure out how to stay out of Russia's way in the skies over Syria.
It was not wholly unreasonable for the U.S. to think Russia could be a partner in the war against ISIS. Yet there was always a fundamental disagreement at the root of that idea. The Obama administration insists Mr. Assad must step down to allow a negotiated end to the country's four-year civil war. Russia, by contrast, says that only Mr. Assad can bring stability to the country and that supporting his government is a prerequisite for peace. Moreover, Mr. Putin has refused to distinguish between various the armed factions fighting the Assad government, calling them all terrorists — including the so-called moderate opposition groups funded by the U.S.
Until this week those opposing views of Mr. Assad's role didn't risk a military confrontation between U.S. and Russia. That changed over the weekend, however, when Mr. Putin ordered his air force to attack Syrian opposition sites in direct support of a Syrian Army ground offensive aimed at taking back territory captured by the insurgents earlier this year. Mr. Putin praised the offensive as a strike against the Islamic State, but it soon became apparent that most of the Russian attacks targeted Syrian opposition forces far from territories controlled by ISIS.
This week Mr. Putin followed up those airstrikes with a barrage of cruise missiles launched from Russian warships in the Caspian Sea. The missiles flew some 900 miles through Iranian and Iraqi airspace to strike their targets in Syria. Meanwhile, Russian military aircraft have entered Turkish airspace on at least two occasions in recent days, prompting strenuous protests from Ankara and its NATO allies. The Turks have long wanted to see Mr. Assad toppled, but they are understandably wary of risking an encounter with Russian military jets to protect their airspace.
Mr. Assad's forces have been substantially weakened after four years of war, and the help he is now getting from Russia, Iran and the Lebanese militia Hezbollah is critical to his survival. Last week that de facto alliance was joined by Iraq when it agreed to allow Russian aircraft to overfly its territory on the way to targets in Syria. But now Moscow's latest moves have made it clear that any possibility for cooperation between the U.S. and Russian forces against Islamic State in Syria is over. Mr. Putin even seems to be taking a perverse delight in frustrating Western plans in the region.
The Obama administration is right to reject any arrangement with Russia that tacitly accepts Mr. Assad's indefinite hold on power. In the past, Mr. Putin has suggested that once ISIS is defeated Russia will consider easing out Mr. Assad as part of a negotiated peace settlement. But nothing he has done since then offers much hope he would ever make good on that promise. On the contrary, he's shown himself to be a master of the bait-and-switch, and his recent actions in Syria are par for the course. When he says "trust me," the U.S. is right to beware.
Nevertheless, the administration needs to reach some form of limited agreement with Moscow to prevent NATO and Russian aircraft operating in Syria from crossing paths. Defense Secretary Ash Carter says the U.S. is open to discussing such issues as which language Russian and NATO pilots would communicate in, which radio frequencies they would use and how they would go about sharing Syrian airspace. Despite Mr. Putin's untrustworthiness in the fight against ISIS, those are still vital safeguards against inadvertent clashes between Russian and NATO aircraft operating over Syria.