Evoking a recent episode in Cairo in which an Egyptian scaled the building housing Israel’s embassy and supplanted Israel’s flag with Egypt’s, Mr. Vaknin said the teams would not allow “any marchers to enter a community, take down the Israeli flag from the roof of the secretariat and replace it with another one.”

The teams were established in 2000, amid the violence at the outbreak of the second intifada, in recognition of the fact that the army could not be in every place at all times. They are required to step back when soldiers arrive. Settler leaders note that the teams, like much of the Israeli population, are made up mostly of army reservists who receive regular training, and they say the teams know how to restrict their operations to defense.

Palestinian leaders have called for popular protests to support their September bid for United Nations recognition. The Palestinian president, Mahmoud Abbas, has eschewed violent confrontation and wants the protests to stay within the confines of Palestinian cities, away from Israeli checkpoints and settlements. But there is fear on the Israeli side that the situation could spiral out of control.

In what some here saw as a rehearsal for September, thousands of Palestinians and their supporters, some wielding firebombs and stones, tried to breach Israel’s northern border with Lebanon and the frontier between Syria and the disputed Israeli-held Golan Heights in May, with a repeat on the Syrian frontier in June. Israeli forces opened fire in both cases, and as many as 33 protesters were killed. Israel maintains that 10 of the dead were killed by land mines on the Syrian side of the fence.

In the May case, some protesters crossed into the Golan Heights before the Israelis opened fire. In June, the military said it fired before protesters reached the fence, aiming at the legs of those who crossed a new ditch the Israelis considered a red line.