Editor's Note: Nic Robertson is CNN's international diplomatic editor. The opinions in this article belong to the author.
(CNN) - During the Bosnian conflict, a particularly pernicious tactic emerged: ethnic cleansing. Whole villages and towns were emptied of their population, based purely on ethnicity.
In 2018, seven years into the Syrian conflict, it seems President Bashar al-Assad has added his own sick twist to the scourge of that Bosnian war crime: chemical cleansing.
His chlorine and likely nerve agent attack in the Damascus suburb of Douma in Eastern Ghouta was his latest drive to flush unwanted families and neighborhoods away.
By November last year, the UN's Syria humanitarian chief, Jan Egeland, estimated Eastern Ghouta was home to an estimated 400,000 people. A few months earlier, it had been agreed that the areas would be designated deconfliction zone -- in theory making it safe from the conflict.
As the bodies were cleared and surviving victims -- doused in water and the noxious chemicals -- were cleared away, Assad was busy declaring victory over the suburb which had become the last rebel stronghold around Damascus. It had managed to hang on to an increasingly dire and dismal existence for almost seven years.
After years of Assad's siege tactics, the suburb's population dwindled: eventually, before the attack, falling well below the 400,000 the UN had estimated late last year. Finally, by cutting supplies altogether, Assad forced its starving citizens into submission.
His gas attack -- killing women and children hiding in basements -- was the final expediter, triggering the expulsion of tens of thousands. According to a tweet from the Russian Embassy in London, more than 25,000 were forced to leave. Syria and its ally Russia have denied banned substances were used in the attack.
But this sort of chemical cleaning is nothing new to Assad.
In the hallowed inner sanctum of international diplomacy, the United Nation's Security Council chamber, US Ambassador Nikki Haley told assembled dignitaries: "The United States estimates that Assad has used chemical weapons in the Syrian war at least 50 times. Public estimates are as high as 200."
It has become a disgustingly common sight now in Syria's conflict to see huge convoys of buses transferring uprooted families and neighborhoods to remote corners of the country.
Many of these areas are euphemistically called "zones of deescalation," but are, in reality, reservations for refugees and rebels, left to await Assad and Russia's next onslaught.
In Bosnia, victims of ethnic cleansing didn't have buses. Often, they fled their burning homes on foot, chased down country lanes and through dense forests by men with machine guns.
By the time the peace deal ending that war was signed in Dayton, Ohio, in 1995, three years of ethnic sifting had separated out the once integrated country in to three ethnically identified regions that 23 years later remain hotbeds of nationalist discontent.
Syria's war has been going on more than twice as long as Bosnia's. More than twice as many people have been killed. Still, Assad isn't done shifting the population to the contours that he wants.
The last vestiges of organized international resistance to his balkanizing tactics was late 2015, -- just before Russia turned the war around for him.
Russian commanders proposed that residents of Eastern Aleppo, then under rebel control, could be bused out to live in other rebel areas. The UN objected, citing concerns it would look like ethnic cleansing.
Several months later, however, as Russia's relentless airstrikes decimated rebel hospitals in the city and turned the tide of the war, buses were called in to do just that. In doing so, they ferried out anyone who couldn't live under Assad's rule.
Not everyone left rebel areas of Aleppo -- and not everyone who lived in Eastern Ghouta -- has fled. But the result of Assad's tactics writ large across the country has been the separation of ethnic and religious groups.
It's hard to tell yet how absolute the divisions have become to compare definitively with Bosnia, but it is enough to flag the dangers of what it could mean for Syria. Whatever the peace formed by Assad and Russia, it will lock in divisions -- storing yet more trouble for the future.
What is clear so far is that Kurds have clung to the north east, their traditional homes; and Assad's Alawi sect and its Shia Muslim and Christian allies hold the capital and their traditional bases -- Latakia and other towns on the coast.
The losers in the population upheaval -- not counting the more than 5 million who have fled the country -- has been the Syria's majority group: its Sunni Muslims. The longer individuals and their families stood against Assad, the further they've had to shift from his power bases.
Most of those cleared from their homes have been bused north to Idlib province, an area that has become Assad's dumping ground for rebel fighters and others he doesn't want.
Like Eastern Ghouta, Idlib is another designated deconfliction zone. But given its high concentration of rebel groups, it seems only a mater of time before Assad and Russia turn up the heat there.
An early indication of that came in the past few months, as rebel groups accused Assad's forces of chlorine gas attacks on civilians.
While this weekend's limited precision strikes targeting Assad's "core" chemical weapons facilities may deter his chemical cleansing tactics for a while, the international community has done nothing to stop him carving up Syria.
Though getting involved in Syria's civil war was not the intention of this weekend's strikes by the US, France and the UK, having placed the conflict under the glaring scrutiny of international attention, the absence of a way of dealing with the core problem of Assad is now even more glaring.
There are two lessons the international community should remember from Bosnia and the Balkans.
The first: Once divided, Syria won't easily -- and may never be -- put back together.
The second: The tyrants causing the mayhem were brought to heel, despite Russia's protestations.
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