These letters have been signed by "Gush Shalom's team for the collection of evidence against war criminals."

The letters were sent to 15 IDF officers with ranks between lieutenant colonel and brigadier general. Gush Shalom identified the officers on the basis of interviews which they gave on local media during IDF operations in the territories. As a result of these operations, Palestinian residents in the territories lodged complaints about IDF behavior; the peace movement based its letters on these complaints.

One such letter, which reached Ha'aretz, was sent a few months ago to a brigadier general who is serving in the territories. The letter refers to a round-up of suspects carried out by the IDF in several villages. In coordination with the Shin Bet security service, family members of leading terror suspects were detained in this round-up - the goal of such arrests was to obtain information about the whereabouts of the terror suspects, and perhaps also to pressure them to turn themselves in.

The Gush Shalom letter warns the officer that "taking hostages is a grave violation of the fourth Geneva Convention." The letter writers declare: "As citizens concerned about the status and image of the state of Israel and the IDF ... we cannot quietly condone such acts. We warn you that evidence about these acts has been compiled, and put in a file that we are preparing."

The file, the letter adds, "is likely to be submitted as evidence in an Israeli court, or to an international war crimes tribunal." The letter ends with a veiled threat: "We hope that from this time forth you will be careful, and refrain from carrying out or taking operational responsibility for more acts that represent violations of international law."

Gush Shalom spokesman Adam Keller confirms that his group is behind the letters. He says that Gush Shalom has established a monitoring group that compiles evidence on the basis of media reports, and work done by human rights groups.

This monitoring group is now comprised of volunteers, but the spokesman indicated that Gush Shalom wants to employ salaried, full-time officials for the work. Keller said that Gush Shalom is now investigating ways to relay information that has been compiled to the International Criminal Court in the Hague. He said that procedures for this new tribunal have yet to be formalized, and so "it isn't clear whether a voluntary group [like Gush Shalom] can submit evidence."

One high-ranking IDF officer, under whose command a number of the officers "warned" by Gush Shalom serve, told Ha'aretz last night that the letters are "an attempt to harm the morale" of soldiers. "This is an exercise in incitement and sedition...and they're trying to foster a sense of personal threat" among officers," he said. The IDF officer added "I'm happy to say that the letters haven't harmed these officers' performance."