On Syria, what will we do — too much or too little? Initial betting is on too little, that is, not enough to change Damascus’s (and Moscow’s) mind on using, with impunity, poison gas.

A year ago, Syria killed nearly 100, mostly civilians, with Sarin gas. To teach Assad a lesson, President Trump launched 59 cruise missiles at a Syrian airbase. The strike lightly damaged the base but, lacking follow-through, taught Assad that he could keep attacking with gas in his civil war. To teach him otherwise, U.S. actions would have to be major and sustained.

I doubt Trump is ready for that. His dilemma: He wants to simultaneously pose tough while pulling the U.S. back from international commitments. Aside from brief, feel-good gestures, he can’t do both. Slap-on-the-wrist strikes like last year’s achieve nothing.

Serious multiple U.S. strikes — say, that crack open Syrian chemical bunkers and release plumes of gas — risk getting us deeper into a complex, multiside war and could easily involve Assad’s Russian protectors. Wars tend to escalate. Russia has put its Black Sea fleet on high alert. Terse verbal escalation has already begun. Will tweets turn into deeds?

The immediate problem is last Saturday’s gas attack on a Damascus suburb that killed some 50 and injured hundreds. Grisly photos show whole families dead — apparently from chlorine plus nerve agent, which causes the foaming mouths visible on the victims. The larger danger is the unhindered proliferation of chemical weapons, facilitated by long-term American indifference.

We have watched repeated gas use. Nasser’s Egypt, then a Soviet client, used gas in Yemen’s civil war in the 1960s. The world barely noticed. Iraq used gas massively against Iran and Iraq’s Kurds in the 1980s, and we, foolishly pursuing Saddam’s friendship, said and did essentially nothing. Gas leaking from damaged Iraqi chemical bunkers may have caused unexplained illness among U.S. troops in 1991. Toxic chickens came home to roost.

Moscow consistently denies that Syria has chemical weapons and called the recent horror “fake news,” but Syria has used poison gas more than 80 times. It works, and no one stops them. Where does Damascus get these weapons or the technology for them? Their primary source must be Russia. At a minimum, Moscow could dissuade Syria from using chemicals.

Russia also practices chemical assassination. In England, a former Russian spy and his daughter were nearly killed by Novichok, a Russian nerve agent vastly stronger than Sarin or VX. Moscow seems to be testing chemical weapons by war in Syria and murder in Britain.

North Korea used VX to kill Kim Jong Un’s half-brother, whom China was hosting in exile as a possible replacement for Kim. Again, where did North Korea obtain VX or the knowledge to produce it? Moscow seems to shrug off the dangers of exporting this technology, but it can easily spin out of Russian control.

The U.S. Army has a tiny Chemical Corps (started in World War I), many of them reservists, to defend against chemical attack. We have no chemical weapons, but how will we stop the Russians (and others) from developing them? We are less prepared for chemical warfare than for cyberwarfare. We are not ready for modern forms of conflict.

One theory holds that if you have nukes, you don’t need gas; the former deters the latter. That seemed to work in the 1991 Gulf War, when Iraq hurled only ineffective explosives at Israel, but has yet to be fully tested. U.S. and Israeli nukes may have deterred Saddam from using his chemical-ready warheads, but would asymmetrical deterrence work if the chemical initiator is backed by nuclear power? Suppose U.S. forces in Syria are hit with chemicals. Would we retaliate if it meant killing Russians?

We were not taken seriously a year ago and now must either escalate or bow out. I foresee wrist slaps and then withdrawal. A president who just proclaimed we will “very soon” withdraw our 2,000 troops from Syria will be reluctant to enlarge our war there. Senator McCain argues that Trump’s withdrawal proclamation emboldened Assad to attack with gas again.

Trump’s call for others to take responsibility in Syria was essentially U.S. abdication of a Middle East role, a role that Russia eagerly covets. Middle East lands will conclude that chemical weapons are part of a normal arsenal.

Trump keeps discovering that domestic and foreign policy are far more complex than business deals. Americans like middle solutions, but middle grounds evaporate in war. LBJ experienced that in Vietnam and had to make up-or-out decisions that ended his career. If you’re in for a dime, you’ll soon be in for a dollar.

By way of contrast, last Monday Israel struck a Syrian airbase that houses Iranian-led fighters, including Iranian Revolutionary Guards and Hezbollah. Russia is furious. Good. But the Israelis make decisions and act on them. Can Trump? Or is he preoccupied with Stormy matters?