Every year, the United Nations ranks the world’s countries according to criteria such as political rights, press freedom and civil liberties. The UN report is illuminating reading, especially for students of the Middle East. Israel is awarded first-world rankings, while its neighbours are near the bottom.

One aim of terrorism against Israel is to derail democracy in the Jewish state by forcing Israelis to choose between being blown up, pizzeria by pizzeria, or enacting such harsh security measures that they lose their democratic bearings. Every suicide bomb carries a message to Israelis: What good is your democracy if it can’t protect you?

So opponents of Israel believed they had scored a propaganda victory last week when Israel said it would begin restricting their movement. Israel is especially concerned about the International Solidarity Movement (ISM), a loose-knit group with branches on university campuses across North America and Europe. ISM’s strategy is to make the Palestinian issue the cause celebre of the protest community, the way East Timor was for many years. The group’s members believe an Israeli crackdown on the ISM will allow the group to paint Israel’s government as illiberal and illegitimate.

In fact, it is not Israel but the ISM that has been exposed as harbouring illiberal tendencies. The ISM publicly advocates non-violence, which accounts for its appeal to idealistic western undergraduates. But the fine print on the group’s Web site makes it clear that "Palestinians themselves will always have, and ought to have, a primary and determining role in ISM’s actions and decisions on the ground." The meaning of that became apparent in March when Israeli troops raided an ISM office in Jenin and captured a senior Islamic Jihad member who was hiding there.

Meanwhile, the two bombers who attacked a Tel Aviv pub last month are believed to have attended ISM events, although the ISM denies they had ever been members of the group. The bombers had been able to penetrate Israeli security because they carried British passports. In its recruiting materials aimed at foreign volunteers, the ISM talks of using "the relative privilege of our passports," and putting "our bodies on the line."

(One ISM member from the United States, 23-year-old Rachel Corrie, was killed in March while trying to prevent an Israeli army bulldozer flattening an area Israel says was used as a staging ground for arms smuggling.)

The ISM admits there "is no central body which dictates policy or activities on the ground" and there are "few restrictions or criteria for becoming a delegate to Palestine." This loose, cell-like structure is convenient, allowing the organization to maintain deniability for the actions of its more radical members.

The sheltering of Islamic Jihad members and playing host to suicide bombers suggest that the ISM is getting careless. This was inevitable. Groups such as this have never accepted a two-state solution to the Israeli-Palestinian conflict. Their advocacy for a Palestinian "right of return" to Israel proper means the end of Israel as the Jewish homeland.

Israel has no choice but to scrutinize "activists" more closely when they appear at the border. Those who genuinely believe in non-violence, but now find themselves barred entry, should direct their anger not at Israel, but at organizations that have blurred the line between legitimate protest and support for terror.