But it’s one thing to shut the door on an individual. quite another to control the movement of money or of ideas. The U.S. Treasury has seized only about $300 trader the January executive order banning fund raising for the right-wing Israeli groups Kach and Kahane Chai. But it’s a simple matter for stateside sympathizers to drop their affiliation with those groups and still keep the faith. The U.S. Jewish community, larger than Israel’s, is just as polarized over the issue of whether Israel should exchange territory for peace with the Palestinians. Americans who believe that Israel’s hold on that land is ordained by God continue to fund the settlements. And there’s no legal reason they shouldn’t; after all, even such strongholds of extremism as Hebron’s Kiryat Arba are still subsidized by the Israeli government. “Hebron is not a political organization, Hebron is a community,” says Mordechai Taub, executive director of the Brooklyn-based Hebron Fund, Inc.

The direct threat of Jewish extremism in America still seems minimal Kahane’s Jewish Defense League was implicated in a string of bombings in the late ’70s and early ’80s, two of them fatal. But the most violent JDL members then shipped out to Israel under heavy FBI pressure. say experts who estimate the current hard core in the United States at about 150 members. And although liberal Jewish leaders in New York have often been threatened since Israel opened talks with Yasir Arafat’s PLO, violence has been limit ed to small bombs placed outside their offices, and most of those bombs have been duds. Kahane Chai sponsored a summer camp in the Catskills for about 200 young would-be members of a West Bank militia. But Camp Meir was not the only summer camp with a rifle range. “We’re not tapping phones on this one,” said a senior law-enforcement source.

More likely, the Jewish community will take the lead in curbing its own radicals. Like the Israelis, many American Jews were appalled at the scenes of revelry that followed the assassination. A backlash has begun. Last week a Brooklyn synagogue was debating whether to sever its ties with a senior rabbi who had suggested last summer that an attack on Israeli leaders would be justified. Ultimately, that kind of reappraisal may be far more effective in curbing the extremists than anything law enforcement can do.