Fearing Israel will seize him, Yasser Arafat (search) fortified his West Bank headquarters with hundreds of concrete-filled barrels and wrecked cars Thursday, saying he's determined to go down fighting.

Israel, which has repeatedly threatened the Palestinian leader, said it has no immediate plan to go after Arafat. One senior Israeli official said Arafat and his aides are being "hysterical" — although Prime Minister Ariel Sharon (search) warned only last month he is no longer bound by a promise to the United States not to harm Arafat.

Palestinian officials said the obstacles in the courtyard are meant to slow tanks and prevent helicopters from landing nearby, but he acknowledged that heaps of scrap metal would not hold back the Middle East's mightiest army for long.

Israel has confined the 74-year-old Arafat to his Ramallah offices for more than two years. In September, Israel's Cabinet decided Arafat should be "removed" and has repeatedly threatened him since then, but never taken any action.

Arafat's aides would not say what spooked the Palestinian leader.

However, he has become increasingly jittery since Israel assassinated Hamas leader Sheik Ahmed Yassin in March. Yassin had widely been considered immune, with Palestinians assuming Israel would be held back by concern about a bloody backlash. After Israel killed Yassin — and Hamas failed to carry out a major revenge attack — Arafat increasingly feared he might be next, his aides said.

Israeli jeeps drive close to Arafat's compound from time to time, and sometimes park outside for hours. Recent visitors to Arafat's compound said he asked them on arrival whether they had seen Israeli jeeps in the vicinity. "They usually come after midnight. Today, they came early," Arafat was quoted as saying.

Arafat said he wouldn't go down without a fight. "I am going to enter this battle with my gun by my side," a visitor quoted Arafat as saying Wednesday over a supper of salads and cooked vegetables. "I will resist until I become a martyr."

Israel has contingency plans for seizing and expelling Arafat, and troops have practiced taking over his compound. However, it is believed Israel would not act without provocation, such as a major attack by Palestinian militants.

Sharon adviser Raanan Gissin said there is no immediate plan to raid Arafat's compound. "We are not going to carry out any operation, but they are hysterical," Gissin said of Arafat and his aides.

Sharon said last month he is no longer bound by a promise to President Bush not to harm Arafat. Although the United States rebuked Sharon for the comments, the veiled threat raised speculation that Israel might target Arafat, whom it accuses of backing Palestinian militants.

Earlier this week, Israeli troops briefly surrounded Arafat's compound during an overnight raid. The army said Arafat was not the target, but Palestinian officials said the veteran leader fears for his life.

"We have a real concern that they (Israeli troops) may come here," said Palestinian Cabinet minister Saeb Erekat.

On Thursday, cement mixers filled hundreds of blue barrels with concrete, and they were then scattered across the main courtyard outside Arafat's compound. Bulldozers also spread dozens of wrecked cars — remnants of previous Israeli raids — across the courtyard.

Security officials said they also set up a new system to alert Arafat's guards if Israelis approach the compound, but gave no details.

Addressing a rally in the Gaza Strip by phone Thursday, Arafat said the Palestinians are ready to meet their obligations under the U.S.-backed "road map" peace plan and hope to resume negotiations with Israel. However, the plan has been stuck since its launch last year, and neither side has kept its promises.

The Palestinians are to dismantle violent groups, and Israel is to freeze settlement construction and remove West Bank outposts. Instead, Israel's Housing Ministry has funneled nearly $6.5 million to outposts and illegal construction in the past three years, a government watchdog reported Wednesday.

Sharon has been weighing his options since his Likud Party on Sunday overwhelmingly rejected his proposal to pull out of the Gaza Strip and four West Bank settlements. Sharon had said the plan would boost Israel's security in the absence of a peace agreement with the Palestinians.