In a major policy speech on Thursday, Sharon said Israel will implement a so-called Disengagement Plan even as efforts to implement Washington's blueprint continued. He accused the Palestinians of not following the "road map" and warned to act in months.
Palestinians have accepted the plan unconditionally while Sharon specified 14 objections.
"If within a number of months the Palestinians will continue not carrying out their part of the road map, then Israel will initiate a unilateral security measure," Sharon said. Israel's justice minister said moves could start within three months.
Palestinians and international mediators oppose any unilateral actions, saying that only a negotiated agreement with the Palestinians can end the violence and lead to peace.
Sharon said that the plan would involve the re-deployment of Israeli occupation forces and changing the distribution of Jewish settlements to reduce the number of Israelis near centres of Palestinian population.
In an effort to quell US fears of unilateral moves, he said Israel would closely coordinate with Washington, its main ally.
Migron settlement is due to be
Sharon also warned that Palestinians would end up with less land if Israel went its own way. Palestinians fear such measures would demarcate the borders of a future state.
Speaking to a security conference in the Tel Aviv suburb of Herzliya, Sharon reiterated calls for Palestinians to dismantle resistance groups fighting Israeli occupation.
In Washington, the White House said it would oppose any unilateral moves that could hinder peace. It urged Sharon and his Palestinian counterpart Ahmad Quraya to "meet very soon, without preconditions".
Sharon vowed to speed up
building of the apartheid wall
Quraya, on his part, said he was disappointed at Sharon's "threats", reiterating that the Palestinians are committed to the "road map".
"This is not a prescription for peace, this is a prescription for more war and more attacks and more isolation and more segregation against the Palestinian people," said Palestinian Foreign Minister Nabil Shaath.US officials are wary of Sharon creating "political facts on the ground" as the apartheid wall Israel is building cuts off parts of the occupied West Bank.
Hamas, which spearheads the Intifada, said Sharon's unilateral disengagement was "worthless" and pledged to continue its struggle.
"Sharon is asking Palestinians to raise white flags, to
surrender," said Hamas founder and spiritual leader Shaikh Ahmad Yasin.
Israel claims the wall is necessary to prevent the infiltration of Palestinian resistance fighters but Palestinians and human rights groups fear it could demarcate the borders of a future state.
In Thursday's speech, Sharon said work on the barrier would be speed up.
The speech comes after weeks of build-up. Sharon began speaking of undefined "unilateral steps" last month, indicating that he might consider moving West Bank Jewish settlements while re-occupying parts the West Bank.
The "road map" requires Israel to freeze settlement activity in the occupied West Bank and Gaza Strip, and calls on the Palestinians to dismantle resistance groups-steps neither side has taken.
Israel has some 150 settlements in the West Bank and Gaza, with about 220,000 Jewish settlers, who are often heavily armed. Palestinians say a crackdown on resistance groups will spark a civil war.
Sharon's declaration came as his government faced intense pressure to take action to end the Intifada. Sharon was elected on a platform to stamp out the Palestinian uprising.