Jessica Ashooh is a scholar at the Atlantic Council and a former senior analyst in the UAE Ministry of Foreign Affairs.

On Aug. 21, 2013, Syrian President Bashar al-Assad used sarin gas to kill 1,429 of his own people, including 426 children, in the town of Ghouta.

I watched these horrific events unfold from an unusual perch for an American: At the time of the attack, I was working as a technical adviser to the United Arab Emirates’ special envoy for Syria. The work entailed accompanying my boss, a former Emirati air force general, to meetings in Turkey and elsewhere to coordinate with the Syrian opposition and the ambassadors of the countries — including the United States — that were assisting them.

Five days after the attacks, we were in Istanbul for an emergency meeting with the Syrian opposition leadership and the group of Western, Arab and Turkish ambassadors known as the “London 11.” The topic of the discussion was the potential international response to the massacre — the deadliest use of chemical weapons since Saddam Hussein gassed the Kurds in the 1980s.

It would have been an emotionally trying meeting under any circumstances — being confronted with the pleas of good, decent Syrian women and men whose relatives had been gassed in full view of the international community. But what made this meeting especially difficult was the realization that no one was coming to help.

Although the United States and Britain were at the time contemplating punitive airstrikes against Assad’s regime as a consequence for breaking President Barack Obama’s “red line,” the more seasoned diplomats in the room instinctually knew that the justice the opposition hoped for would not be forthcoming.

Watching Robert Ford, the courageous and principled U.S. envoy for Syria at the time, prepare the Syrians for disappointment was painful and showcased the human consequences of what happens when the American Atlas shrugs. Experiencing the episode purely as a spectator was like a distressing dream.

This week, Assad again apparently used nerve gas against his people — years after claiming to have given up all his stocks to the United Nations for destruction. At least 70 are dead, once again including children.

For their part, Iran and Russia, the self-appointed guarantors of Assad’s behavior, are now running scared. Understanding the seriousness of the charges, they are doing all they can to distance themselves from the events or provide desperately implausible explanations. They are worried for the first time in years about what the international consequences might be for their client now that Obama and his laxity are out of office.

(Sarah Parnass,Julio Negron/The Washington Post)

The young Trump administration is at a decision point that will define how the world views the untested president. While the White House and State Department rightly condemned the attacks, U.S. presidents are judged on their actions. President Trump has a rare opportunity to quickly and forcefully right one of the most consequential failings of the Obama administration and restore U.S. credibility.

Trump should order targeted, punitive strikes against the Assad regime to degrade his capability to harm his own people. It is important to understand, however, that this action would not entail operations targeted at overthrowing Assad. That would be both impractical and unnecessary. Instead, regime military assets such as runways and airfields should be targeted. These targets are away from civilians and pose little risk of further casualties or suffering to the Syrian people. While their loss would be costly to Assad, they would not topple him. Furthermore, while considerations of the Russian response are prudent, the reality is that Russia is unlikely to retaliate militarily against the United States on behalf of Assad, an unruly client whose intransigence has time and again embarrassed the Russians on the global stage.

Such strikes could also be an important force for leverage in the stalled peace process. After that fateful Istanbul meeting in 2013, the second most frustrating experience of my career was sitting in the Geneva II negotiations of 2014, trying to reach a peace deal with no military leverage to speak of. Assad, with the connivance of Russia, simply stonewalled the talks and ran down the clock, secure in the knowledge that there would be no consequences for his behavior.

Dictators do not come to the negotiating table out of the goodness of their hearts. They come because they believe they can get a better deal there than on the battlefield. As a consummate dealmaker, Trump should understand this and do what is necessary to create the leverage that sets the table for real peace. This in turn can only come through a sincere political solution in which the Syrian government acknowledges and accommodates the legitimate aspirations of its people, including the right to choose their leader.

In his inauguration speech, Trump promised that “carnage stops right here and stops right now.” Syria presents an urgent opportunity for him to turn his words to action.