According to Palestinian sources, a clandestine meeting late on Thursday night between the Israeli Prime Minister, Ehud Barak, and the Palestinian president, Yasser Arafat, focused on this joint campaign. It followed talks in Amman earlier in the day between Mr Arafat and King Abdullah of Jordan.
The initiative is believed to have come from Mr Barak, who telephoned the royal palace while the king was hosting Mr Arafat. Both Israeli and Palestinian sources confirmed yesterday that the Barak-Arafat summit took place at the Prime Minister's private residence in Kohav Yair, a commuter town close to the old "Green Line" border east of Tel-Aviv. It lasted more than an hour and was only the third time since his return from exile in 1994 that Mr Arafat has entered Israel.
The Jordanian Prime Minister, Abdel Raouf Rawabda, revealed this week that his security services had uncovered a large arms cache in the southern Jordanian town of Karak. Intelligence sources believe they were going to be smuggled across the border to Israel and the West Bank.
Jordan has recently closed the Hamas office in Amman and arrested some activists. Senior officials, who were abroad, are threatened with arrest if they return. Israeli-Jordanian relations have improved since Mr Barak came to power three months ago. In a previously unannounced meeting, the Jordanian Foreign Minister, Abed Khatib, visited Mr Barak's Jerusalem office on Tuesday.
Mr Arafat, too, is keeping a tight rein on Hamas, which is thought to have been behind recent car bombings in the Israeli towns of Haifa and Tiberias. In the past two weeks, Israel has transferred another 7 per cent of the occupied West Bank to Palestinian civilian control and released 199 Palestinian security prisoners.
Mr Barak signalled on Thursday, however, that he intends to drive a hard bargain on Jewish settlements. He alarmed the Palestinians by appointing Shilo Gal, a leading West Bank settler, as his adviser on settlement matters. Mr Gal said he saw his job as "limiting the damage".
Hamas is as determined as ever to challenge any compromise with the Jewish state. Its spiritual leader, Sheikh Ahmed Yassin, said in Gaza this week that he would make no deal with Israel so long as it occupied any of historic Palestine. He predicted that "this weak peace process will not last too long".