On Tuesday, Israel's Independence Day, hundreds of settlers travelled to IDF outposts and took them over. Well, they took over the kitchens and cooked the soldiers barbecue dinners.

But not all was sweetness and light between the army and the settlers. At least in one spot on the West Bank, no one was doing anyone any favours. A clash between security forces and a group of youngsters from Yitzhar left at least two soldiers wounded by stones and a growing number of settlers under threat of arrest.

The IDF claims that the settlers were planning to attack a nearby Palestinian village. The settlers claim that all they wanted was an Independence Day picnic at a nearby spring.

The IDF issued a statement saying that "the violence towards soldiers was an inexcusable crossing of the lines, especially on Independence Day", but the truth is that there is nothing new about this level of violence between the security forces and some of the settlers. Official settler spokesmen denounced violence against the IDF but with the same breath said it was unrepresentative of the majority of people in Yitzhar, which only last month produced a cadet who received the Officer's School order of merit.

The problem, said a senior officer, is that while most settlers do not go against the army, "the radical margins are steadily widening".

While Yitzhar and a few other radical settlements are routinely involved in violent clashes with the army, the security forces are aware that things may get a lot worse in three months' time, if the government decides to cave in to the Obama administration and extend the 10-month freeze period on building in the West Bank.

The IDF high command has tried to minimise friction by sending its police force, rather than soldiers, to accompany the civilian building inspectors charged with enforcing the "freeze order". But spontaneous breakouts like the one in Yitzhar caught them unawares and brought civilians and "regular" soldiers into direct confrontation.

The next stage could be another rash of religious settler soldiers refusing to obey orders. But that could be the least of the army's worries. With the last round of Palestinian rioting over, the IDF believes that the Palestinian leadership in the West Bank currently has no interest in a violent uprising. Instead, the PA wants to concentrate on building the infrastructure for a state and gaining international support. That poses its own challenges but it is still preferable to violence.

The IDF's commanders are warning that what could suddenly change the entire picture is a serious violent provocation by radical settlers. Something bigger than burning fields, uprooting olive trees and vandalising mosques. Something could set the West Bank on fire again.