President Obama says he doesn’t want to turn the Syria conflict into a proxy war. Unfortunately, that’s already happening, as combatants join the battle against the Islamic State with radically differing agendas that could collide.

Let’s look at the confusing order of battle: The United States has decided that its strongest partner against the Islamic State is a Syrian Kurdish force known as the YPG. But Turkey, nominally our NATO ally, says the YPG has links with what it claims is a Kurdish terrorist group. How’s that going to work out? No answers yet.

Russia, meanwhile, contends that it is fighting the Islamic State, alongside forces loyal to President Bashar al-Assad. But Russian warplanes have been bombing Islamist rebel groups that are covertly supported by the U.S., Turkey and Jordan — and these brigades are fighting back hard. The rebels are posting videos bragging about their success with U.S. anti-tank missiles. The battle looks eerily like Russia’s war in Afghanistan, in embryo. Where’s it heading? No answer there, either.

Saudi Arabia and Iran have been fighting by proxy in Syria for nearly four years. This may be the most toxic conflict of all, because it feeds the Sunni-Shiite sectarian inferno that is immolating the Middle East.

Look across the map of shattered Syria and you see contradictory coalitions and partnerships. With so many powerful military forces gathering in the same area, the danger for accidents and miscalculations is large.

Why is this proxy war escalating at the same time the outside powers are holding diplomatic talks about resolving the conflict? The U.S., Russia, Iran, Turkey and Saudi Arabia sent representatives to Vienna last week to explore the political transition they all claim to favor. The meeting was not encouraging: No Syrian combatants attended, and the outside powers disagreed sharply about what a transition should look like.

“Fight and talk” is a recurring cycle in Middle East conflict. So perhaps the recent military escalation is the prelude to diplomatic negotiations, as each side tries to extend its territory and strengthen its bargaining position before serious talks begin. We should be so lucky. But both Assad and the rebels seem as unready for compromise as ever.

Studying Syria from north to south, it’s clear where “deconfliction,” as the military puts it, is needed to avoid unintended disaster.

On the northern front, the U.S. needs to deepen its consultations with Turkey as it escalates support for Syrian Kurdish forces and their Arab allies. President Obama is sending fewer than 50 Special Forces operatives to Syria, but make no mistake, this is a significant commitment. The U.S. troops will need air support — not just to bomb the Islamic State, but for resupply, rescue if they get in trouble, and perhaps to enable the cycle of intelligence-driven “night raids” that was so devastating in Iraq.

What does Turkey think about this expanded U.S. role on its border, especially after the decisive election victory last Sunday by the sometimes Kurdophobic President Recep Tayyip Erdogan? Pentagon officials say the Turks should be reassured, because the U.S. will now have greater oversight of the YPG’s 25,000 fighters and can prevent supplies from getting to the PKK, which Turkey views as a terrorist group. It’s a reasonable argument, but it needs Ankara’s assent.

On Syria’s southern border with Jordan, the U.S. has quietly helped train a rebel coalition known as the Southern Front, which claims 35,000 fighters in 54 brigades. Last week, Russian warplanes attacked some of those U.S.-backed forces at Al-Harra in southwest Syria, the site of a former Russian signals-intelligence station captured by the rebels. This is crazy. Moscow and Washington should look to de-escalate the situation, rather than torch it more.

But in the inexorable logic of the Syria conflict, worse is ahead. Maj. Essam al-Rayes, the spokesman for the Southern Front, told me in a telephone interview Tuesday that his forces expect a new Syrian onslaught this week, backed by Russia, to recapture ground south of Damascus. This pursuit of “victory” only helps the extremists.

What’s over the hill, if the outside powers don’t find a path toward deescalation? Here’s one grim hint: I had visits over the past several weeks from leaders of Kurdish political movements in Iran and Syria who envision the day when a greater Kurdistan dissolves the borders of those nations, as well as Turkey and Iraq.

If Russia, Iran, Turkey and the other proxy fighters don’t help put the pin back in this grenade, a more devastating, regionwide explosion lies ahead.

David Ignatius’ email address is davidignatius@washpost.com.