The Pentagon announced last night that U.S. naval forces in the Persian Gulf region had been ordered to begin "intercepting" commercial shipping to or from Iraq and Kuwait to enforce the United Nations' economic sanctions against Iraq. The orders allow the Navy to board and search cargo ships and tankers and, if necessary, take them into custody to prevent them from reaching their destinations.

The disclosure of the interception orders came just hours after President Bush announced that King Hussein of Jordan had told him that his country would adhere to the international economic sanctions against Iraq and close its key port, Aqaba, to goods bound for Iraq. The Navy's interception zones include the approaches to Aqaba.

Bush and Hussein met at the president's summer home in Kennebunkport, Maine, yesterday for about two hours. Afterward, Hussein refused to say publicly that he had agreed to stop Iraqi goods from passing through Aqaba. But Bush, speaking to reporters after meeting Hussein and the Saudi foreign minister, Saud Faisal, said he was "very pleased" by Hussein's commitment to enforce the sanctions, and he said flatly that Hussein had told him Jordan would close Aqaba to Iraqi goods.

Bush said he believed the differences between the United States and Jordan, which a week ago "appeared to be grievous," had been narrowed. He added, "I would put this under the heading of very encouraging developments."

Reports reaching the United States indicated that the flow of goods through Aqaba had already slowed to a virtual trickle.

In a harsh personal attack yesterday, Iraqi President Saddam Hussein accused Bush of being a "liar" intent on "plundering" the Arab world's oil wealth, and he warned that any American troops who clash with those of Iraq "will go home in shrouded coffins." Saddam was responding to Bush's sharp personal attack on Saddam in a speech to Pentagon workers on Wednesday, in which he said the Iraqi leader had lied and his troops had committed atrocities.

Asked about Saddam's remarks yesterday, Bush said he has seen the latest charges from the Iraqi leader but declined to respond to them in kind. Bush said they did not contain "any concrete proposals to which I feel a necessity to respond."

One day after Saddam proposed a peace agreement that would meet virtually all of the conditions of Iran, with which Iraq has been in a state of war for 10 years, Iranian President Ali Akbar Hashemi Rafsanjani said he appreciated the peace offer but reiterated Iran's demand that Iraq withdraw from Kuwait and said the two issues are separate.

The Defense Department said the president "has authorized forces to participate in the multinational effort that will intercept ships carrying products and commodities that are bound to and from Iraq and Kuwait."

Consultations are going on now with other nations that have expressed interest in enforcing an embargo on Iraqi trade by naval interdiction, according to Pentagon spokesman Pete Williams.

The Pentagon statement said Bush took the action after the exiled government of Kuwait "requested that the U.S. government act as coordinator of the ships participating" in the embargo.

More than two dozen U.S. Navy warships are operating in the region in the Persian Gulf, Gulf of Oman, Red Sea and eastern Mediterranean Sea. The supercarrier USS Dwight D. Eisenhower, with escort and support ships, is in the Red Sea, within easy reach of Aqaba. The Navy's orders set the "primary zones" of interception in the northeastern waters of the Red Sea, including the Gulf of Aqaba, and much of the Persian Gulf.

Bush first ordered a blockade mounted on Sunday, and the precise wording of the orders had been under debate since then.

In Washington, the Pentagon announced that preliminary cost estimates for Operation Desert Shield, the deployment of U.S. forces to the Persian Gulf, would be nearly $1.2 billion for the next six weeks alone. Military sources said a total of 45,000 to 50,000 Marines are on their way to Saudi Arabia to join tens of thousands of Army troops and Air Force personnel already on the ground or in transit.

Meeting briefly with reporters before returning to Jordan, Hussein denied he had come carrying a message from Saddam, as had been widely reported. He said he had not come as an envoy "on behalf of anyone in the area."

A Jordanian official said Hussein had sought the meeting because the king believed Jordan's role in the two-week-old crisis had been misinterpreted by the American news media and he wanted to set the record straight with Bush.

Shipments of goods through Jordan to Iraq emerged as a key sticking point. Hussein said his country was seeking clarification from the United Nations about the degree to which food is exempted from the sanctions.

Some food has gotten through the port of Aqaba since the sanctions were announced, but a Jordanian official said this only involved shipments that had been purchased before the sanctions were ordered.

Hussein said no shipments were going through the port "as of the moment," and a Jordanian official said there had been no violations of the sanctions, despite great economic hardship to his country.

Secretary of State James A. Baker III, who attended yesterday's meetings, tried to play down the dispute over food shipments, indicating it was proper for the Jordanians to seek clarification from the United Nations because the trigger mechanism for exemptions had not been defined.

"It's not a loophole," Baker said. "It's the way the sanctions were written by the United Nations when they voted 13 to 0 to impose them."

Despite Bush's optimistic assessment of the session with Hussein, the meeting appeared to have had tense moments. After emerging from Bush's oceanfront home about 2:15 p.m., a somber Hussein called it "very frank, open, and candid."

Bush's public stance toward Hussein, whose words of support for Saddam during the crisis have irritated the administration, has alternated almost day by day, displaying both the longstanding friendship that exists between the two leaders and the disappointment administration officials have felt.

Hussein said he came away from the meeting "with a clearer idea of what the president's thinking is."

Because Jordan gets virtually all its oil from Iraq and sends the bulk of its exports to Iraq, enforcing the sanctions will come at a hefty economic cost.

"We are asking them to flush their economy down the drain," said a U.S. official. "The economic implications for Jordan are staggering."

The United States is prepared to help assemble a package of support for Jordan from other countries, including Saudi Arabia, but Hussein said this had not been discussed.

Saudi Foreign Minister Saud, who along with Saudi Ambassador Bandar bin Sultan spent nearly two hours with Bush, also said compensation for Jordan was not discussed during his meeting with Bush.

The Saudi foreign minister sounded pessimistic about possible diplomatic solutions to the conflict. "We still hope conflict can be avoided," he said.

Hussein sounded equally pessimistic, saying he had not given up hope only because "without hope, you can't get anywhere. And the dangers are such that it's unthinkable to contemplate the idea of giving up and not trying one's best to resolve this problem . . . ."

A Jordanian official said Hussein's goal is to "get things back to normal in the region," and suggested that the price of peace might have to be higher oil prices worldwide.

He said Hussein was prepared to tell Bush yesterday that events had moved too quickly in terms of the military buildup, the international condemnation of Iraq and the increasingly shrill and personal rhetoric. This, the official said, left Saddam no maneuvering room and could lead to conflict that would unleash Arab fundamentalism and radicalism.

He added that Hussein still believed there was room for compromise around three principles: Iraqi withdrawal from Kuwait; return of the Kuwaiti ruling family; and negotiations "within an Arab context" to resolve the Iraq-Kuwait dispute. He said Jordan believes Saddam has a legitimate grievance against the Kuwaitis on overproduction of oil.

Bush said Turkey's President Turgut Ozal had given him a "somewhat optimistic" report about the impact of the economic sanctions and said he did not believe the Iraqis could last very long with "true international isolation."

Pentagon officials said that on Monday two U.S. F-15s on patrol over northern Saudi Arabia turned back an unidentified aircraft coming from the direction of Kuwait by locking onto the craft with their missile-targeting radar.

Other Pentagon officials yesterday detailed the expanded Marine deployments. The Marines are from the 7th Marine Expeditionary Brigade at Twentynine Palms, Calif., the 1st Marine Expeditionary Force at Kaneohe Bay, Hawaii, and the 4th Marine Expeditionary Brigade at Camp Lejeune, N.C. A military official said a brigade is about 15,000 to 17,000 Marines. The first two brigades would fly to Saudi Arabia while the 4th MEB was moving aboard a 13-ship amphibious fleet from Norfolk.

The Pentagon also announced that elements of the Army's 3rd Cavalry Regiment at Fort Bliss, Tex., began departing yesterday for Saudi Arabia.

Staff writers Patrick E. Tyler, John M. Goshko and Spencer Hsu contributed to this report. Balz reported from Kennebunkport, Hoffman from Washington.