KENNEBUNKPORT, MAINE, AUG. 10 -- President Bush, embarking today on a 25-day vacation here at his oceanfront home, issued a stern warning to Iraq not to send out tankers loaded with oil in an effort to break the international trade embargo.

The president refused to call the growing buildup of naval forces in the Persian Gulf and elsewhere in the Middle East a blockade but said he remains prepared to "do whatever is necessary to see that exports from {Iraq} . . . do not go forward."

Asked if U.S. ships would stop Iraqi tankers, he replied, "Put it this way: I would advise Iraqi ships not to go out with oil," adding, "there are a lot of things going on right now that I don't feel like commenting on."

Administration officials have avoided using the term blockade because it is considered as act of war and, therefore, not appropriate to the present crisis. Speaking just before a majority of Arab nations, meeting at a summit in Cairo, voted to send troops to Saudi Arabia in an effort to prevent an Iraqi invasion, Bush brushed aside Iraqi President Saddam Hussein's call for a jihad, or holy war, as the "frantic ploy" of a radical leader who has been "backed into the corner" by world opinion.

"He is so isolated in the world, so backed into a corner by world opinion, which is almost 100 percent against him, that he has to find some mechanism to rally support," Bush said aboard Air Force One. "His problem is in the Arab world and Muslim world, as well as it is in the rest of the world."

Later, Bush received an update on the Arab League summit from national security adviser Brent Scowcroft, who spoke to Bush by telephone from Washington while the president was out in his speedboat Fidelity.

White House press secretary Marlin Fitzwater said in a statement that the administration is "pleased by the very strong condemnation" of Iraq and the decision by individual Arab states to send forces to support Saudi Arabia and other countries in the gulf.

The move by Arab forces to join U.S. and Saudi troops drew a sigh of relief from administration officials who said from the outset that American GIs could not be alone on the ground if Bush was to continue to receive strong domestic support. One official noted, "Even if the non-U.S. forces were small, it is the symbolism that counts. At the end of the day, we are going to be the largest presence there. If there is no one with us, it would be a political disaster."

Bush said he remained worried about the status of Americans detained in Iraq and Kuwait but said he would not "invite further harassment" of the Americans by "elevating the value of any . . . citizen." He refused to describe the detention of the Americans as "a hostage situation," but said there have been "very disturbing reports of violence" against citizens of a number of nations.

Before leaving Washington, Bush sent Congress two new executive orders covering the economic sanctions against Iraq and a letter "consistent with the War Powers Resolution" notifying congressional leaders of the deployment of forces to Saudi Arabia. The administration does not recognize the constitutionality of the resolution and couches its reports to Congress as voluntary, not pursuant to that act.

Bush told Congress that while he did not believe hostilities were imminent, U.S. forces were prepared to remain as long as needed. "There is no evidence right now that Saddam Hussein would be foolish enough to cross that border," Bush told reporters en route to Maine.

But he added that the United States and other nations are "up against a man who is known for his brutality and irrationality and who has taken a step that, though widely condemned, has still not been reversed."

The president met with Defense Secretary Richard B. Cheney and other national security aides before leaving Washington. Scowcroft and Secretary of State James A. Baker III will arrive here Saturday for a day of consultations. Baker, who returned from overseas late tonight, is expected brief Bush on his his meetings in Turkey and with NATO foreign ministers in Brussels.

Bush is to return to Washington Wednesday for a full-scale military briefing, probably at the Pentagon, and offficials said the White House is considering but is not nearing a decision on another, broader address to the nation on the longer term implications for the crisis.

Some of the president's political advisers have suggested that Bush, in order to maintain broad support, will need to lay out more clearly the risks and potentially serious problems the country will face in an extended war of wills with Iraq. One official noted, "It is going to take a lot of presidential communication and effort to keep the country on board. I don't think there is a public awareness yet of the dimensions of this, and as that begins to take hold, support is going to start wavering."

Staff writer Ann Devroy in Washington contributed to this report.