The respectable public standing of Jewish nationalists arrested last weekend - and the mass nature of the murder that some of them are suspected of planning - has shocked Israel.
The situation has thrown Israel's militant right into a rare position of defensiveness.
Unlike the youthful or fanatic Israelis arrested in recent months for anti-Arab violence, whoever booby-trapped five Arab buses in east Jerusalem last Thursday were highly professional operatives. Their handiwork could have resulted in scores of deaths.
Far from being on the margin of society, the more than 20 people arrested reportedly include many who are central figures in the Jewish settlements on the occupied West Bank and Golan Heights, as well as an Army officer and at least one high-ranking Army reservist.
Israel radio reported that only three of those arrested are accused of actually placing the bombs, and that the others are being questioned about possible complicity.
Stunned by the disclosure and concerned about its possibly negative impact on the future of the settlement movement, settlement leaders debated heatedly for hours Sunday over whether to give legal and moral backing to those arrested. They decided to offer their support, while asserting confidence of the men's innocence and condemning the bomb plot.
''Whoever wanted to booby-trap those buses could in fact have joined the Palestine Liberation Organization because it is only they who would profit from it,'' declared Elyakim Haetzni, one of the most prominent leaders of the settlement movement.
The bomb plot was apparently in retaliation for an attack on an Israeli bus this month and other recent acts of Arab terrorism. It was clearly designed not just to wreak havoc, but also to demonstrate to Israel's Arab population that it is dealing with an avenging force from which there is no hiding.
The buses, all belonging to the Kalandia bus company, had been parked Thursday night outside the homes of the drivers in Arab villages widely scattered around Jerusalem.
The perpetrators not only knew where the drivers lived, but were also able to penetrate the villages at night without awakening residents or dogs and afix sophisticated explosive devices beneath the buses.
The bombs were set to go off in the afternoon when the buses would be filled with passengers. Unknown to the perpetrators, one of the buses had been chartered to take a group of Jewish visitors from abroad on a tour of West Bank settlements. Another was to carry a group of German tourists.
Disaster was avoided only by the infiltration of an agent into the group by the Shin Beth, Israel's equivalent of the FBI. Security forces arrived at the villages before dawn to dismantle the bombs and in one case had to flag down the bus driver who was getting off to an early start.
The existence of a Jewish underground based in West Bank settlements was first mooted four years ago when car bombs maimed two West Bank mayors in almost simultaneous blasts occurring in two separate locations. An Israeli sapper was blinded trying to dismantle a bomb outside another mayor's house.
Government officials rejected the possibility of an organized Jewish underground, asserting that at most a few individuals were involved.
According to press reports, the then head of the Shin Beth had suggested after that attack that his organization, normally deployed against Arab subversion, begin monitoring extreme right-wing Jewish circles by means of tracking, telephone tapping, and other means. However, then Prime Minister Menachem Begin, according to these reports, permitted only one surveillance measure: the opening of mail.
In view of this background, the fact that the latest arrests took place under a different prime minister, Yitzhak Shamir, is noteworthy. Although he had served for a while as commander of the most extreme right-wing underground movement in Israel's pre-state days, the so-called Stern Gang, Mr. Shamir has evidently given the Shin Beth a free hand to monitor Jewish underground activity. He told the Cabinet Sunday that the bomb plot would have resulted in a human tragedy of major proportions and inestimable political damage to Israel.
But Shamir warned in a public speech against any attempt to capitalize on the bomb plot to curb West Bank settlement. He said the settlers are pioneers who are creating historical facts that will last for generations .
Another ex-Stern Gang figure, member of parliament Geula Cohen, also condemned the plot. ''We have our own state and there is no room for an underground,'' she said. ''If the bombs had gone off, they would have booby-trapped the country, not just the buses.''