It’s no real surprise when the government of Iran breaks its word, so why do European leaders keep accepting it? Call the latest debacle “the tale of the tanker that could.”

Back in July, British Royal Marines stopped an Iranian oil tanker, Grace One, that was plainly bound for Syria in violation of European Union sanctions.

Note that these EU sanctions were on the Syrian government, over its countless atrocities in the long civil war — not on Iran.

Gibraltar authorities detained the ship for weeks, even after Iran responded by seizing a UK-flagged tanker, the Stena Impero, in the Strait of Hormuz.

But in mid-August the ship was quietly released from Gibraltar — after Iran gave written promises it wouldn’t take its 2 million barrels of oil to Syria. American authorities then sought to seize the tanker, but no Mediterranean nation would assist, as it was officially bound for Turkey.

Yet the ship, renamed Adrian Darya One, has instead docked at … Tartus, Syria. And Iran’s foreign ministry even says it has now delivered its cargo “on the Mediterranean coast.” Meanwhile, the Stena Impero remains in Iranian custody, though several of its crew were released this week.

UK Foreign Secretary Dominic Raab has summoned the Iranian ambassador for a firm talking-to. That’ll show’em!

Lesson No. 1: Iran can’t be trusted an inch.

Lesson No. 2: Europe’s preferred Iran policy — appeasement — is not only weak, but futile.