A U.S.-Iran peace deal signed days ago is already fraying as Israel pounds Lebanon and Iran hedges on its commitments — and ordinary Americans are left holding the bag for yet another Middle East negotiation that serves everyone except them.

Vice President JD Vance postponed his trip to Switzerland for follow-up talks Friday, as Israeli airstrikes killed at least 18 people in Lebanon and Hezbollah destroyed three Israeli tanks, killing four soldiers. The deal was supposed to stop the fighting. It didn't. The question isn't whether this agreement holds — it's why American credibility and resources keep getting mortgaged to broker settlements that regional actors have no intention of honoring.

The preliminary agreement, signed by President Trump and Iranian President Masoud Pezeshkian, calls for a cease-fire "on all fronts, including Lebanon." Israel isn't a party to the deal. Prime Minister Benjamin Netanyahu made clear Thursday that Israeli forces will remain in a "security zone" in southern Lebanon "as long as Israel's security needs require it," AP News reported. Israel's far-right National Security Minister Itamar Ben-Gvir went further: "All of Lebanon must burn," he said, per the BBC. So much for the cease-fire.

Hezbollah, also not a signatory, ambushed Israeli forces near Kfar Tebnit, destroying three Merkava tanks with guided missiles and killing four soldiers — one of the deadliest strikes since March, according to the New York Times. Israel responded by hitting 80 targets across southern Lebanon and the Bekaa Valley.

Iran's commitment looks equally shaky. Supreme Leader Mojtaba Khamenei said Trump pursued the agreement "out of desperation" and that future negotiations "will not mean acceptance of the enemy's position," NBC News reported. Iran has warned it won't abide by the deal if Israel continues its Lebanon campaign — which Israel is doing.

The deal's immediate payoff was reopening the Strait of Hormuz, with over 12.5 million barrels of oil shipped through the waterway Wednesday night, per AP News. Trump said he signed to avoid "economic catastrophe" from skyrocketing oil prices. But the long-term tab is staggering: KABC-TV reported the deal includes a potential $300 billion fund for Iranian rebuilding and sanctions relief. That's American leverage — and potentially American money — spent propping up an arrangement already collapsing on launch day.

Vance defended the deal Thursday, arguing relief to Iran is conditional: "As they dial up their good behavior, we can dial up the economic relief. If they dial down their good behavior, we can turn it off," he said, per KABC-TV. He also rebuked Israeli critics: "If I was in the cabinet of the Israeli government, I might not be attacking the only powerful ally that I have anywhere left in the entire world," the New York Times reported.

Conditional leverage only works if you're willing to walk away. Neither party in Washington has that track record. Some congressional Republicans criticized the deal for giving Iran too much economic relief while punting on the nuclear program, the Times reported. But the deeper problem is bipartisan: the assumption that the U.S. must remain the region's permanent mediator, underwriting arrangements foreign actors can break at will.

France's foreign minister urged the U.S. to pressure Israel to respect the deal, per the BBC. Ambassador Mike Huckabee backed Israel's strikes, posting: "Ceasefire happens when Hezbollah stops shooting & killing," AP News reported.

The Strait of Hormuz is open and oil prices have dipped. That's tangible. Everything else — the 60-day negotiation window, the Swiss resort talks, the promises about nuclear inspections — is a familiar Middle East mirage. The signatories can't even get their own allies to stop shooting. When the next escalation hits, will Washington finally walk away — or write another check?