A UN report detailing the "massive and systematized" violence perpetrated by Syrian President Bashar Assad against his own people "shatters the notion that the regime is somehow a lesser evil" than ISIS.

That is according to Emile Hokayem, a senior fellow at the International Institute for Strategic Studies, who said on Tuesday on Twitter that the report is "inconvenient" for those who argue that Assad should stay in power for the sake of creating stability and defeating ISIS and Al Qaeda.

The report concluded that widespread and systematic torture at the hands of the Assad regime — which, according to a Syrian-government defector codenamed "Caesar," had killed over 10,000 people as of July 2014 — amounts to "extermination as a crime against humanity."

The report said:

The accumulated custodial deaths were brought about by inflicting life conditions in a calculated awareness that such conditions would cause mass deaths of detainees in the ordinary course of events and occurred in the pursuance of a State policy to attack a civilian population.

Russia, a staunch Assad ally, has sought to depict the regime as a bulwark of peace and stability against the so-called terrorists, who threaten Assad's power.

Because Russia does not differentiate between jihadist groups and the "moderate opposition," however, rebel groups backed by the US, Turkey, and Saudi Arabia have been aggressively targeted by Russian airstrikes since late September.

ISIS, meanwhile, has largely been spared.

Russian Airstrikes 29 JAN 07 FEB (1) More

Rebel ranks are therefore dwindling. It has set the stage for a situation that the regime and its allies have been working toward for years: a choice between ISIS — whose crimes are well-documented and publicized — and Assad, whose atrocities in torture chambers across the country were systematically covered up and largely unknown to the world.

The regime has made no effort, on the other hand, to hide its practice of barrel bombing civilian targets such as schools, marketplaces, and hospitals. Whereas roughly 10% of civilian fatalities in Syria last year were at the hands of ISIS, the regime was responsible for at least 75% of all civilian deaths in Syria in 2015, according to humanitarian news group IRIN.

Meanwhile, the regime's detention program — a squalid prison system where, according to the UN report, torture and summary executions are deliberate and commonplace — is ongoing.

View photos A Syrian refugee child looks on, moments after arriving on a raft with other Syrian refugees on a beach on the Greek island of Lesbos, January 4, 2016. REUTERS/Giorgos Moutafis More

After nearly five years of war, however, the international community has become desensitized by the bombing campaign and distracted by the emphasis placed on defeating ISIS by those sympathetic to Assad — and the West.

"Assad all along pursued a strategy of gradual escalation and desensitization that, sadly, worked well," Hokayem wrote for Foreign Policy.

US Secretary of State John Kerry accused Assad and his allies last month of being the "primary source of death, torture and deprivation" in the conflict, which has killed more than 300,000 people since it erupted in March 2011.

But the Obama administration has been steadily softening its stance on Assad's removal for years, a policy shift that culminated in December when Kerry said that the US is "not looking for so-called regime change" in Syria.