Munich ? The abiding image from last weekend’s security conference here was of Prime Minister Benjamin Netanyahu theatrically brandishing a piece of an Iranian drone shot down over Israel a week before — and starkly warning Tehran: “Do not test Israel’s resolve.”

Are Israel and Iran heading toward war, in their new jockeying for influence amid the rubble of Syria? Probably not, but a delicate game of brinkmanship has certainly begun. Policymakers in Washington, Jerusalem, Moscow and Tehran are struggling to define and communicate the rules.

The Israel-Iran confrontation is the most dangerous new factor in Syria, which has become a gruesome cockpit once again after some months of relative quiet. The Syrian regime is now trying to crush resistance in Ghouta, east of Damascus, where rebels once had support from the CIA but are now struggling on their own. The bloodbath there has been horrific, and the U.N. Security Council on Thursday debated a resolution for a 30-day cease-fire. Russia resisted, evidently wanting to complete the bloody campaign.

This grim new phase of the Syrian conflict is a replay of the siege of Aleppo — with the added new danger of a regional war between Israel and Iran. It’s this latter problem that most concerns U.S. and Israeli officials, especially after the shootdown of an Israeli F-16 during a retaliatory strike after the Iranian drone incident.

A senior Trump administration official this week summarized the deterrence strategy against Iranian forces in Syria: Israel must maintain its freedom of action to strike Iranian threats anywhere in Syria; the U.S. and Russia should expand the buffer zone in southwest Syria where Iranian-backed forces aren’t allowed to operate. That exclusion zone is now about 10 kilometers; the U.S. wants to widen it to 20.

But this simple formula doesn’t address the larger questions that are lurking in the new Israel-Iran standoff. Should Israel work more closely with Russia to decrease Iranian influence? (And does Moscow have the power to deliver?) Should America use its military presence in eastern Syrian to check Iranian forces?

There’s also a controversial new twist that’s being discussed quietly by some U.S. and Israeli officials. If it’s unrealistic to expect that U.S. military forces and their Syrian Kurdish allies will indefinitely occupy Syrian territory east of the Euphrates, then should the U.S. begin working to gradually restore the authority of the Syrian government to that part of the country?

“Return of the state, not return of the regime” is how some officials are describing this approach. There’s an important caveat: This strategy cannot mean restoration of power for President Bashar Assad, whose massacres of his people won’t be forgiven by millions of Syrians. Assad’s toxic role was dramatized by this week’s slaughter in Ghouta.

Experts in Washington, Moscow and Tel Aviv are weighing whether there might be an eventual deal between America’s key ally in Syria, the Kurdish-led “Syrian Democratic Forces,” and a reformed Syrian army and state. That Kurdish-government alliance might be a better bulwark against Iranian influence than an unsustainable American occupation; it could also be the backbone of a reformed Syria.

To check Iranian influence in Syria, the U.S. needs a coherent strategy whose pieces fit together. The U.S. has leverage but appears unsure how to use it, which tempts rivals such as Russia, Turkey and Iran. “The most expensive option in the Middle East is doing ‘nothing.’ This simply imposes greater costs on future policymakers,” argues Norman Roule, a former chief of Iranian operations at the CIA and the Office of the Director of National Intelligence. He recently became an adviser to United Against Nuclear Iran, an advocacy group.

Iran, meanwhile, is replicating in Syria the disciplined, ideological power base it developed in Lebanon, Iraq and Yemen. Roule argues that the Iranians thrive on three factors to project power: internal political chaos, a beleaguered Shiite minority, and a logistical pipeline to Tehran. All three are present in Syria, Roule argues.

A case study of how Iran builds this proxy power is a militia called the “National Ideological Resistance in Syria,” often dubbed a “Syrian Hezbollah.” It’s relatively small, mobile and intensely motivated. According to Syrian analyst Aymenn Jawad al-Tamimi, it has fought in Damascus, Palmyra and Aleppo and has established affiliates in northeast and southwest Syria.

The Syria shooting gallery, and the jostling of foreign proxy forces there, reminds me ominously of Lebanon before the Israeli wars of 1982 and 2006. America, Russia and the regional powers need to chart a pathway toward stability or this catastrophe will get worse.

— David Ignatius is a columnist for Washington Post Writers Group.