THE UNITED NATIONS Security Council has repeatedly voted for sanctions to deter Iran from obtaining a nuclear weapon. The five permanent members of the Security Council plus Germany have devoted years of diplomacy to slowing Iran’s quest for an atomic bomb. The hints from Israel of impatience with all this, and a desire for a military strike, are growing.

All of which makes it passing strange that Ban Ki-moon, the United Nations Secretary General, might appear in Tehran to attend the conference of the Non-Aligned Movement, which opens Aug. 26. Already, the street lamps are being painted and hotels prepared for the arrival of heads of state as the Islamic republic thumbs its nose at Western sanctions and isolation. Iran is taking over chairmanship of the movement for the next three years.

The conference promises to be a festival of resistance to the United States, the United Nations Security Council and Israel. Nuclear weapons? Iran has signaled plans to use the conference to defend its right to enrich uranium, which it claims is for peaceful purposes. Sanctions? Iran is busy repainting tankers in the Persian Gulf to evade restrictions on oil exports, concealing money transfers and importing illicit materials for its nuclear program through third countries.

Iran continues to supply weapons to the besieged regime of Syrian President Bashar al-Assad, which subverted the Security Council’s peace initiative. And don’t expect any muffling of Iran’s long-standing and poisonous anti-Zionism.

Perhaps Mr. Ban entertains a hope that he can single-handedly persuade Iranian President Mahmoud Ahmadinejad and Supreme leader Ayatollah Ali Khamenei to end their quest for nuclear weapons. That assumes that the United Nations leader has more clout than anyone else who has tried. We’re told that Mr. Ban sees this as a crucial moment for a diplomatic last-ditch effort. But it doesn’t seem even remotely likely to succeed.

More likely, Mr. Ban will be forced to endure public lectures from the Iranian leaders about their right to enrich uranium, and rants threatening to wipe Israel off the map. If he shows up — he has not yet announced plans to attend, but sources say he is determined to go — will Mr. Ban then stand up and object? To his credit, Mr. Ban has in the past forcefully lectured Mr. Ahmadinejad about adhering to Security Council resolutions. But if he does so again, will Iran or anyone in the Non-aligned Movement be listening? Probably not.

The Non-Aligned Movement was founded during the Cold War by nations that formally didn’t want to be part of either superpower bloc, although many were anyway. Since then, it has run out of gas. Firebrands like India were transformed into world powers in their own right. Today, it is a very loose regional group of developing nations allied with the Group of 77 at the United Nations, but not much more. By attending the Tehran conference, Mr. Ban will dignify a bacchanal of nonsense, undermine the work of the Security Council and probably get nothing in return.