Stop. Just stop.

Five years ago, Obama declared that Assad must step down. Ignoring him, Assad went all out to crush the rebels, both those we backed and the Islamist terrorists.

Obama then drew a “red line,” declaring that Assad’s use of chemical weapons would lead to U.S. strikes. But when Obama readied military action in 2013, Americans rose up and roared, “No!”

Reading the country right, Congress refused to authorize U.S. military action. Egg all over his face, Obama again backed down.

When Assad began losing the war, Putin stepped in to save his lone Arab ally, and swiftly reversed Assad’s fortunes.

Now, with 10,000 troops — Syrian, Iraqi Shiite militia, Hezbollah, Iranian Revolutionary Guard and Afghan mercenaries — poised to attack Aleppo, backed by Russian air power, Assad may be on the cusp of victory in the bloodiest and most decisive battle of the war.

Assad and his allies intend to end this war — by winning it.

For the U.S. to reverse his gains now, and effect his removal, would require the introduction of massive U.S. air power and U.S. troops, and congressional authorization for war in Syria.

The time has come to recognize and accept reality.

While the U.S. and its Turkish, Kurdish and Sunni allies, working with the Assad coalition of Russia, Hezbollah and the Iranians, can crush ISIS and al-Qaida in Syria, we cannot defeat the Assad coalition — not without risking a world war.

And Congress would never authorize such a war, nor would the American people sustain it.

As of today, there is no possibility that the rebels we back could defeat ISIS and the al-Nusra Front, let alone bring down Bashar Assad and run the Russians, Hezbollah, Iran and the Iraqi Shiite militias out of Syria.

Time to stop the killing, stop the carnage, stop the war and get the best terms for peace we can get.