The world can focus only on one crisis at a time, or so it seems.

The Syria crisis gave way to the Ukraine crisis, which then gave way to the Nigeria girl-kidnap crisis, which then made way for the Iraq crisis.

Back to Syria. Remember the “red line” President Obama drew and then said the United States would strike militarily at Syria if it used chemical weapons against its people? The Syrians did. The president blustered, threatened to hit them hard, then asked Congress for permission.

Then came the Russians, who then brokered a deal that persuaded the Syrians to get rid of the gas they used on their citizens.

You know what? It now appears the last of the weapons are gone. Destroyed. We never fired a shot at them.

It’s not entirely clear that all the weapons are gone, as the New York Times editorial notes with caution. The “known weapons” have been removed and destroyed. It remains to be seen whether the entire cache of WMD is gone.

Still, it is worth noting that Obama’s critics had it wrong when they blasted him for failing to act on the “red line” threat, even though Republicans kept insisting the president seek congressional approval before he did anything. The president did that — but it wasn’t good enough to suit the critics.

Barack Obama took office in January 2009 vowing to bring diplomacy back as a tool to help stem international crises. He’s sought to do that, all the while deploying military might when needed. Drone strikes have been effective at killing terrorists. Let us not forget what happened in early May 2011 when the SEALs killed Osama bin Laden in that daring raid to wipe out Terrorist No. 1.

The Syrian crisis is far from over. People are still dying in a civil war. Bashar al-Assad’s forces have taken back the momentum in the struggle.

One key element of that crisis — those dreaded WMD — has been removed. As the New York Times editorial notes: “President Obama’s critics excoriated the deal, but they have been proved wrong. The chemical weapons are now out of the hands of a brutal dictator — and all without firing a shot.”