The consequences of inaction in Syria are about to become alarmingly clear

Meet the key players in Syria's civil war
Meet the key players in Syria's civil war

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    Meet the key players in Syria's civil war

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Meet the key players in Syria's civil war 02:22

Nic Robertson is CNN's international diplomatic editor. The opinions in this article belong to the author.

(CNN)Over the past few weeks, the shadow cast by Syria's conflict has been growing longer and darker.

Many of the conflict's protagonists will mingle at a security conference this weekend in Munich, Germany.
Should Russian Foreign Minister Sergey Lavrov bump into US Defense Secretary James Mattis in the venues-clogged hallways, or should Iranian Foreign Minister Javad Zarif meet his Turkish counterpart -- let alone collide with Israeli Prime Minister Benjamin Netanyahu -- it would be a pretty safe bet to assume they won't start tearing chunks out of each other.
    But it is becoming increasingly urgent that these competing actors sit at a table and start talking.
    A recent succession of spikes in the conflict affecting all these parties on multiple fronts could be a harbinger of far worse to come.
    Today, the veneer of proxies separating Russian and American forces is wafer thin -- so too between Turkish troops and America's Syrian allies -- as Iran's entrenchment collides with Israel's interests.
    In the past two weeks, US forces have twice repelled Syrian government fighters backed by Russian mercenaries, killing more than 100 in one encounter.
    Last weekend Israel unleashed its biggest attack yet on the Assad regime and its Iranian allies deep inside Syria.
    Turkey lost troops, a tank and a helicopter during its new offensive over the border in Syria fighting American allies, the Kurds.
    Russia had a fighter jet downed, triggering outrage in Moscow and heavy retaliatory strikes over the capture and killing of a pilot.
    Bashar al-Assad's forces have significantly escalated their attacks on a Damascus suburb they've laid siege to for four years.
    Rebels claim that Assad is using chemical weapons -- including chlorine -- to attack them. French President Emmanuel Macron has threatened airstrikes on Assad's forces if he continues chemical attacks.
    So much volatility over such a short period of time hints that the wheels are coming off.
    The failure of the Trump administration to truly engage last year, the failure of President Barack Obama several years earlier to enforce his "red line" and the failure of Russia to look beyond its own desires has pushed the Syrian conflict to its most dangerous place yet.
    Conflicts of interest that were sidelined and subjugated to the joint aim of defeating of ISIS are now exposed.
    In the first large-scale engagement between Assad's forces and US soldiers alongside their Syrian rebel partners, more than 100 of their attackers were dispatched forever in airstrikes and artillery fire. This was no accidental clash -- and we may see more like it.
    US Special Forces fighting ISIS in Syria
    ISIS in Syria_00013222

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    The proximity of US and Russian-backed forces increases the likelihood of mutually destructive battlefield engagements.
    Since the beginning of this year, Mattis, Secretary of State Rex Tillerson and Nikki Haley, US ambassador to the United Nations, have taken a far more robust line with Assad and Russian President Vladimir Putin than they had done for most of Donald Trump's first year in office.
    The turnaround in US posture was enough for a former minister of one US Mideast ally to remark to me: "Finally America has found its feet and policy" on the region's longest-running civil war.
    After almost a year of silent wandering in the wilderness, absent of stature, both the State and Defense departments are now standing up to Russia.
    They loudly accuse Moscow of failing to curb Assad's battlefield use of poison gases, and of failing to make Syria's dictator end the killing.
    Estrangement -- even from the distant frosty relations Obama had with Putin -- has grown in part because Trump didn't engage diplomatically on Syria. His response was on the battlefield -- aimed exclusively at ISIS. Syria's other problems took a back seat.
    And those same problems -- US backing of Syria's Kurds over ally Turkey's objections, Iran's use of Syria's civil war to advance its own hegemonic regional interests, Israel's pent-up frustrations at Iran's expansionism, Turkey's battle with the Kurds, Assad's continued bloodletting even in the suburbs of his own capital, and Russia's intent to impose an unworkable peace -- are all coming to a head.
    This conflict has become multiple cauldrons of competing interests, stewing in Syria's fetid 7-year war. No one person knows what's in each of the simmering pots, and no one can predict what happens when one pot boils into the next.
    While the United States has sat on the diplomatic sidelines for the best part of a year, Russia has pushed Syria peace talks on its own terms.
    They have tried to usurp UN peace talks in Geneva, Switzerland, with their own version in Sochi, inviting compliant opposition and imposing a peace that has no chance of holding.
    In short, the past year's focus on fighting ISIS has done nothing to bring Syria close to stability, but it has left the United States and Russia on an inevitable collision course.
    What will make this year different, however, is that the two countries through their proxies have now advanced to an agreed-upon line of military separation -- the Euphrates River.
    It was established, along with a military deconfliction hotline, to ensure their forces didn't clash and to keep their fragile anti-ISIS partnership intact in Syria.
    Now that both sides have reached the Euphrates, Russia insists that ISIS is defeated and therefore it's time for US forces to leave. Mattis has made a point recently of insisting the opposite: ISIS is not defeated, and it's too soon for US troops to pull out.
    Robert Ford, the last US ambassador to Syria, argued last year that the United States has no strategic interest in keeping troops in Syria. There was nothing to gain and much blood and treasure to lose.
    America's Syrian rebel allies, on the other hand, fear that with US troops gone, Assad's forces will crush them. They want the East of the Euphrates as their own -- to show they can run a democracy.
    The United States is also finally awakening to ally Israel's major concern in Syria: Iran's entrenchment in the conflict.
    According to recent reports, Iran has loaned Assad $4.6 billion in credit and invested $16 billion propping up the dictator since 2012.
    While ISIS, the refugee crisis, the killing of innocents, and the shelling of hospitals by Russia has kept the West distracted, Iran has burrowed deep into the Syrian state, and no one has figured out how this might be undone.
    As long as Iran poses a perceived threat to Israel, that single issue alone could trigger an escalation on any number of other fronts.
    We see the true scale of the mess from conflicting interests in Syria. It's not that no one has a plan for peace, but that no one has figured out how to untangle the complications and head off the coming escalation in a country already exhausted by this brutal war.