A child receives treatment after a chemical attack in northern...

A child receives treatment after a chemical attack in northern Syria on Tuesday, April 4, 2017. Credit: EPA / Stringer

American indifference has ended. In four minutes, President Donald Trump reversed the shameful Barack Obama doctrine of indifference to the Syrians.

Hours after two U.S. Navy destroyers in the Mediterranean launched 60 Tomahawk missiles, some Washington politicians poured scorn upon the use of American military force.

Far-left critics condemned the unilateral action, assailing Trump for not first seeking congressional authorization. Seeking to tether Trump in futile partisan debate, such anti-war positions have proven lethal on a genocidal scale. Congress under President Obama oversaw the slaughter of Syrians, failing both the Syrian people and America’s moral compass for two consecutive administrations.

The sheer vanity of the Obama doctrine of inaction sealed the fate of nearly 500,000 souls, dismantling the families of more than 10 million displaced in and outside Syria, impacting Europe. While the perpetrators of these deaths were Bashar Assad, Russia and the Islamic State, the profound moral regret is uniquely American. We are the only ones with sufficient backbone and brawn to oppose the culling of humanity and with a conscience to care.

In striking Syria, America reminds the world that international laws govern and no power is beyond reach. Not Assad, not Vladimir Putin’s Russia and not Hassan Rouhani’s Iran. President Trump’s airstrikes in Syria also remind Americans of who we really are: the world’s moral arbiter.

The woeful Obama doctrine preached non-intervention, hasty disengagement from ill-fated wars, a deaf ear to Iran’s 2009 brutally crushing of a peaceful revolution; and apathy to the Arab Spring that never was.

In the Muslim majority world, the Arab world in particular, America was defined by Obama’s administrations as at best an unwilling, and at worse, an unavailable ally. Confidence in the region plummeted and new wars were born. On Trump’s election, some Middle East opinion makers justifiably quipped that Obama would not be missed.

Why should the United States police the world, Americans fairly may ask? Why should our sons and daughters die defending the vulnerable and the voiceless? Because we are a God-fearing, moral and benevolent people, and because with the blessings of our wealth and military might we accept great responsibility.

Syria’s war of seven years reveals what it means when America abandons moral arbitration. America’s so-called “leadership from behind” — dillydallying just shy of impotence — revealed the confusion of our less powerful allies when denied their leader, America. Unchallenged until Trump’s Syria strikes, Russia, Iran and Syria have wreaked havoc. If Russian tanks tomorrow invade Lithuania and Estonia, it will be because years of American disengagement emboldened Putin, who has annexed Crimea and is seeking to annex Ukraine. A pipe dream? For Europeans, it’s a full-scale threat: Ask the Swedes who have revived conscription.

Time to remind these renegades of the long leash they have exploited. They are to be reined in, no matter how they snap and bite. Progressives will decry Trump’s use of force and no doubt other missions to see to the demise of Assad’s career as a Genocidaire-in-Chief.

“What comes next?” hand-wringing liberals bleat. What America does best: We do whatever it takes. President Trump will seize prime control of Syrian airspace, followed by a ground invasion of both American and international coalition forces. With Assad deposed, America can secure a cease-fire, then turn to diplomacy, aid, conflict resolution and alliance building. The United States is not intimidated by Russia, Iran or Islamic State.

That’s right, America: Baby, we are back.

Qanta A. Ahmed is a member of the Council on Foreign Relations. She is the author of “In the Land of Invisible Women: A Female Doctor’s Journey in the Saudi Kingdom.