The following editorial appeared Friday in the Dallas Morning News:

The U.S.-Russian agreement to dismantle Syria’s chemical weapons arsenal marks an enormous step toward breaking the superpower impasse that has helped Syria’s civil war spin out of control over the past two years. But much work remains, including administering justice to those responsible for an Aug. 21 sarin gas attack that killed more than 1,400 people.

Russia stands staunchly behind its Syrian government ally’s claim of innocence, insisting that rebels launched the attack. The United States, Britain, France, Australia and NATO maintain that dictator Bashar Assad’s forces did it and must be held accountable.

Even the officially nonpartisan U.N. secretary-general, Ban Ki-moon, stated in off-the-cuff remarks last week that he believed Assad “has committed many crimes against humanity.”

Evidence points overwhelmingly to the government’s responsibility. The trajectory of the sarin-laden warheads leads back to a mountaintop government military complex overlooking Damascus, an area never held by rebels.

Chemical weapons are highly specialized. Only Syrian military personnel were known to have them and the expertise to mix them and attach sarin warheads to rockets without killing themselves in the process.

Russia’s dubious argument requires us to believe that the rebels captured these weapons and turned them against their own fighters and supporters rather than against their government enemy.

Russia also wants us to believe that the Assad regime experienced a sudden pang of conscience over this supposed rebel attack and decided to relinquish all of its chemical weapons. This is a family dictatorship that thought nothing of killing more than 10,000 people in the city of Hama during a previous anti-government uprising in the early 1980s. The Assad regime has a decades-old record of complicity in bombings, assassinations and hostage-taking in neighboring Lebanon.

Yet Russia contends the Damascus government wants to come clean because of an atrocity it says the rebels committed. The explanation requires a skeptical world to discard everything we know about the Assad dictatorship’s bloody past.

The U.S.-Russia deal is far from complete. The U.N. Security Council still must pass a resolution outlining severe consequences if Syria fails to comply. The path forward is fraught with difficulties as international inspectors prepare to trace, confiscate and eventually destroy Syria’s chemical weapons stockpiles while civil war rages all around them. There’s a distinct possibility that Assad will mimic the stalling and shell-game tactics that Iraqi dictator Saddam Hussein used to thwart U.N. inspectors in the 1990s.

The United Nations must insist on a thorough investigation into who ordered the Aug. 21 attack. Once that’s established, a war crimes tribunal must convene and administer swift justice to the guilty.

Contact editorial page editor Maria Parham at