The single reason the latest hijacking could take place is that Iran has established itself as sponsor and sanctuary of the community of Islamic radicals from which this particular gang apparently was drawn. Terrorists of whatever stripe need help and a home. They need a place to plan their crimes, a place to get the money and the guns, and a place to escape to afterwards.

Revolutionary Iran has inspired, set up and guided the principal groups of terrorists now active in the Middle East. The group that kidnapped the Kuwaiti airplane was trying to spring 17 Iranian- tied Iraqis whom Kuwait had jailed for bombing the American and French embassies last year. In two recent episodes in which planes were pirated to Tehran, the Iranians apparently set the skyjackers free. Without Iran, terrorism in the area right now would be the work simply of hip-pocket operators and lone crazies.

It follows that the most effective way to fight terrorists is to deny them a quiet place to make ready and to hide. How? Military attacks on the perpetrators or their patrons may have their uses in certain circumstances, although, as the Shultz- Weinberger debate on the issue is tending to show, these circumstances are likely to be few. Political action against the gunmen and their seconds should be constant, including boycotts by civil aviation. Intelligence must be shared and the expectation created that in a crisis all other countries will close ranks. Publicity and denunciation can help.

In the latest incident, various pressures applied by governments that Iran is interested in cultivating seem to have helped incline the authorities in Tehran to limit the damage somewhat. But this was not done in time to save the lives of two Americans and to prevent other innocents in the plane from being subjected to abuse and horror.

President Reagan yesterday singled out Kuwait, praising its "firm stand" in refusing to buckle to the hijackers. Let us -- and we mean this newspaper -- also praise Kuwait. Ten years ago Kuwait was the patsy for the Palestinians, who were in their hijacking phase. "Looking for a comfortable, safe place to escape to after your next multiple murder?" we inquired rhetorically after Kuwait had welcomed its fourth band of Palestinian killers in a few months -- "Try Kuwait."

The Kuwaitis have in the interim accepted the stern obligations of good international citizenship. Last year they jailed the bombers and now they have stood up to the hijackers. For them the stakes are tremendous, vulnerable as they are to Iranian rage. They deserve immense respect.