The U.S. military supply line in the Persian Gulf is showing signs of strain and military stockpiles should be increased before any American offensive is launched against Iraq, three senior U.S. Marine generals have warned in the past week.

The generals also cautioned that war in the gulf would be bloodier than many Americans may realize. "If we have to do anything militarily, it's going to cost American lives. We ought to all be sitting and praying that the sanctions and the diplomatic process win out," Lt. Gen. Ernest T. Cook Jr., commander of the Marine Corps Combat Development Command, said in an interview at Quantico.

Gen. Alfred M. Gray, the Marine commandant and a member of the Joint Chiefs of Staff, made similar comments in an extemporaneous speech to a group of former Marines in Peekskill, N.Y., on Nov. 1, hours after returning from an inspection trip to Saudi Arabia. He also sharply criticized the logistics system in the gulf, according to several persons who heard Gray's remarks.

President Bush's expansion yesterday of the U.S. military presence in the gulf will send about 45,000 additional Marines to join the estimated 45,000 Marines already deployed in Saudi Arabia and on ships in the Persian Gulf.

The commandant declined to discuss his speech with The Washington Post, but the Marine Corps made available Cook and Maj. Gen. Matthew P. Caulfield, deputy commander for warfighting, both of whom were in Peekskill.

Gray believes "we don't have as much there as we ought to have. . . . We are not as ready as we should be or could be," Cook said.

The Marines went to the Persian Gulf in August with a two-month stockpile of supplies, Cook said, but "after 60 days we need help just like everybody else" from the logistical system under Gen. H. Norman Schwarzkopf, commander of U.S. forces in the gulf region. "We have to make sure that the system that's in effect is going to take care of our needs as well as everybody else's," Cook added.

Since Operation Desert Shield began in early August, the United States has moved hundreds of thousands of tons of supplies to the gulf. But the intensity and violence of modern warfare mean that stockpiles of ammunition, spare parts and other materiel would dwindle quickly if all-out combat erupts.

Gray's concern with supply lines and stockpiles is "not an unusual thing," Caulfield said, and is a common preoccupation of commanders preparing for possible battle. "Clearly, logistics is the hard part of fighting a war," Cook added.

Logistics is "a concern of all of us because we are . . . stretched farther than we've ever been in our nation's history in terms of trying to sustain a large force in theater," Cook said. "We have nine classes of supply, and we're concerned about all nine." Ammunition, class 5, is probably at the top of the list, he said.

The Marines and other services are prepared to fight now, Cook added, "but we can be better." Cook quoted Gray as saying that "time is on our side" and that "the more we build our logistics base there, the more we do in-country training with our forces there, the more combat effective we are going to be."

Gray wants "to counter an exuberant feeling that we ought to get this thing over in a hurry," Cook said. U.S. forces could capture Kuwait City, he added, "but it's not going to be easy. You'll pay a price for it." The commandant warned last week that Iraq is "formidable" and should not be underestimated.

The colorful and outspoken Gray told the Peekskill crowd, according to five who were in the audience, "There are four kinds of Marines: those in Saudi Arabia, those going to Saudi Arabia, those who want to go to Saudi Arabia, and those who don't want to go to Saudi Arabia but are going anyway."

Added Cook, "That one almost brought the house down."

This week, the Marines for the first time in this crisis notified about 800 combat reservists that they will be called to active duty. Foreshadowing that announcement, Gray last week told his audience, which included many reservists, that some would be sent to Camp Lejeune, N.C., or Camp Pendleton, Calif., and "you'll stay there as long as I want you there." Cook said the comment was "sort of a typical Gen. Gray statement," and that the commandant is aware that such decisions are the province of the president and secretary of defense.

The three Marine generals said they are generally pleased with the deployment of U.S. forces in the gulf and with Marine morale.

Asked about reports that Iraq could flood defensive trenches with burning chemicals or set fire to an oil slick to thwart an amphibious landing along the Persian Gulf, Cook said, "I don't think it's as frightening as it sounds, to be honest. For instance, if somebody dumps oil over the water and lights it, you can always back off and let it burn itself out."