Mr Barak, who was scheduled to have breakfast with Tony Blair this morning, is awakening expectations in Israel that negotiations with Syria and the Palestinians will be concluded in a far shorter space of time than previously expected.
Danny Yatom, a senior adviser to Mr Barak, said yesterday that the Israeli-Syrian negotiations would resume in a matter of weeks. "I estimate it won't take very long," Mr Yatom said about the starting date for talks. "It's closer to weeks than days."
Mr Barak said on his trip to Washington that 15 months would be enough time to know "whether we have a breakthrough and are really going to end the conflict".
Syria is showing signs that it is giving up its long-held position as the leader of the "rejectionist" camp in the Arab world. President Assad led the opposition to Egypt's peace treaty with Israel in 1978 and the Oslo accords between the Palestinians and Israel in 1993.
Earlier this month Syria told eight small Damascus-based Palestinian organisations opposed to peace with Israel that they should abandon armed struggle and set up political parties in the event of an Israeli-Syrian peace treaty.
None of the groups has carried out armed attacks in recent years, but the Syrian vice- president, Abdel Halim Khaddam, told them they would have to hand over their weapons. In another sign of Syria's change of stance the number of attacks on Israeli troops by Hizbollah, the highly effective Lebanese Islamic guerrillas, in south Lebanon has decreased since Mr Barak took office. Syria has told the guerrilla fighters to limit their long-range mortar attacks on Israeli forces. Mr Khaddam reportedly said Hizbollah would also have to disarm after a peace treaty.
The new Syrian policy is likely to effect President Assad's relations with Iran, which is a long-term backer of Hizbollah.
The two biggest Palestinian rejectionist parties, the Popular Front for the Liberation of Palestine and the Democratic Front for the Liberation of Pal-estine did not meet Mr Khaddam. But their leaders, George Habash and Nayef Hawatmeh are to meet Yasser Arafat, the Palestinian leader, soon. They will discuss a joint strategy for negotiating a final peace agreement with Israel.
The two fronts carried out bloody attacks against Israel in the 1970s, but their opposition to peace with Israel in recent years has been mainly passive. Mr Hawateh has said he wants to return from exile and live in Palestine.
Mr Arafat is nervous of being squeezed into making concessions by the newly strengthened Israeli-US alliance. He is also concerned that talks between Israel and Syria will take precedence over negotiations with the Palestinans. Saeb Erekat, the senior Palestinian negotiator, said he was disappointed Mr Barak had not spoken of stopping "unilateral acts, including settlement activities".
Mr Yatom said Israel would prefer to postpone two withdrawals from the West Bank brokered under the terms of the Wye Agreement last October. But he added: "The Prime Minister said more than once that if Arafat rejects the proposals, the state of Israel will apply Wye as written." Mr Barak and Mr Arafat are to meet at the weekend.
Renewed negotiations with Syria were expected once Mr Barak won the Israeli election in May. What has caused surprise to diplomats is President Assad's warm welcome to Mr Barak and an apparent willingness to enter talks immediately about an Israeli withdrawal from the Golan Heights and a settlement in south Lebanon. During Mr Barak's five days of meetings in the US, Mr Clinton committed himself to making peace agreements with Syria and the Palestinians the centrepiece of his last 18 months in the White House.
Mr Clinton is to meet Mr Barak every four months to assess the progress.
Mr Barak also won more aid from the US as well as up to 50 new jet fighters.
Annual US military aid to Israel will rise from $1.9bn to $2.4bn, if Congress approves. A further $1.2bn will be allocated to finance the Israeli pullback from the West Bank under the Wye Agreement.
The new Israeli Prime Minister was guaranteed a warm welcome in Washington because of the relief felt at the defeat of his predecessor, Benjamin Netanyahu. Mr Netanyahu once said that the US viewed him as "the Saddam Hussein of the West".
Mr Barak was lavished with praise. Madeleine Albright, the US Secretary of State, told him that his "first visit as Israel's leader has been an enormous success".
Mr Barak's diplomatic offensive is encountering little criticism in Israel, although the opposition Likud party said yesterday that he was making himself vulnerable to US pressure by setting a 15-month timetable for success in talks with Syria and the Palestinians.
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