While President Trump largely won bipartisan and international praise Friday for the missile attack he ordered on a Syrian air base, he also opened himself up to hard questions. The first is the toughest: What’s his administration’s policy on Syria?

“Military action is not the end, it it the beginning. And the question has to be: How does this relate to a larger strategy of how do we deal with Syria,” former Secretary of Defense Leon Panetta said Friday.

Thursday’s attack marked a reversal by Trump on Syrian policy. In September 2013, before he was a presidential candidate, Trump tweeted: “President Obama, do not attack Syria. There is no upside and tremendous downside. Save your ‘powder’ for another (and more important) day!”

But his attitude changed within hours of this week’s chemical weapons attack by forces loyal to President Bashar Assad’s government, which the World Health Organization said killed 84 civilians and injured 546 in the town of Khan Sheikhoun.

Trump apparently was moved by video of the aftermath.

“It was a slow and brutal death for so many,” the president said. “Even beautiful babies were cruelly murdered in this very barbaric attack. No child of God should ever suffer such horror.”

But experts cautioned that while the U.S. strike by 59 Tomahawk missiles on the Shayrat airfield may provide short-term retribution, a missile attack is not a policy.

“There may be some emotional satisfaction that something was done, but this remains the problem from hell,” said Daniel Benjamin, a former State Department coordinator for counterterrorism who now teaches at Dartmouth University. “And deeper engagement (in Syria) is anything but easy. And it’s unclear if it is wise.”

Retaliating in a “proportional” way, as both the administration and some Democrats described the U.S. response to the gas attack, drew bipartisan political support, even from Trump critics like Sen. Dianne Feinstein, D-Calif., who said the attack “was a limited but necessary response to those heinous acts, and I hope the intended message was received.”

But Feinstein and others also demanded the administration outline a coherent policy for Syria. What that might be is one of many questions now at the forefront of U.S. foreign policy.

What’s the next step for the United States? “You have to combine diplomacy with force,” said Bruce Jentleson, a former State Department adviser who has been involved in some back-channel diplomacy with the Russians in the Middle East. “If it is only force, then you keep getting egged into these types of situations, over and over.”

What could trigger a future U.S. retaliation? Panetta, who was also director of the CIA and a Democratic representative from Monterey, said Trump has set a precedent that if Syria uses chemical weapons, the U.S. will respond.

But instead of chemical weapons, what if Syria employs “barrel bombs (stuffed with shrapnel and nails) to hit hospitals?” Panetta asked. “Do we now assume the responsibility every time” to respond militarily?

Does Thursday’s strike give us a hint into Trump’s foreign policy? Not yet.

“The overriding concern is that Trump completely flipped from one day to the next on an issue of significant national security that he’s been talking about for years,” Benjamin said. “Yes, we should all be deeply affected by those pictures (of children suffering from the chemical attack). But I have very little confidence that he is thinking one, two or three moves ahead, which is what a president has to do.”

What does the U.S. want Assad to do? That seems to be changing. Last week, Secretary of State Rex Tillerson said the “longer-term status of President Assad will be decided by the Syrian people.”

But after the gas attack, Tillerson said, “Assad’s role in the future is uncertain, clearly, and with the acts that he has taken, it would seem that there would be no role for him to govern the Syrian people.”

Will Trump get congressional approval before using force again? In August 2013 — two years before declaring his candidacy, Trump tweeted, “The president must get Congressional approval before attacking Syria — big mistake if he does not!”

That didn’t happen on Trump’s watch.

On Friday, House Minority Leader Nancy Pelosi, D-San Francisco, wrote to Speaker Paul Ryan, D-Wis., and asked him to call Congress home from recess to debate authorization for the use of force against a sovereign nation. Not much chance of that happening as long as there is a GOP Congress and president.

Are the Russians really mad — or did they know the missile attack was coming? Russia, which along with Iran is Assad’s main supporter, offered a series of mixed messages after the attacks.

Russian President Vladimir Putin said the attack was a “significant blow” to U.S.-Russian relations, and Russia asked the United Nations Security Council to consider whether the U.S. missile attack violated international law.

But the United States gave Russia more than an hour’s notice of the attack, and there is no indication that it lost troops or equipment in the strike.

Panetta said: “The action we took sent a very important signal to our adversaries and allies that the U.S. is going to take military action when we feel it is necessary. It’s an important message to send to Putin because he was sensing weakness with us.

“But the Russians are not interested in having a major confrontation with the United States,” Panetta said. “They will resort to diplomatic moves, but I don’t think they’re going to” risk anything more than that.

Joe Garofoli is The San Francisco Chronicle’s senior political writer. Email: jgarofoli@sfchronicle.com Twitter: @joegarofoli