President Clinton ordered what he called a "strong, sustained series of airstrikes" against Iraq yesterday in response to Iraqi President Saddam Hussein's continued defiance of U.N. weapons inspections.

Meanwhile, Harvard affiliates with foreign policy and military expertise said to attack would be of dubious value in hindering Iraq's long-term military capability.

The attack, which began without warning at about 5 p.m. Eastern Standard Time, was designed to cripple Iraq's ability to produce nuclear, chemical and biological weapons, Clinton said in a nationally televised address from the Oval Office.

In Baghdad, witnesses said to missiles hit the capital after midnight Iraqi time, one near one of Hussein's biggest palaces. A defiant Hussein issued a statement that "wicked people" had bombed several targets, and he urged the Iraqi people to "fight of the nation, enemies of humanity."

"Operation Desert Fox", as the Pentagon dubbed the assault, was intended to last up to four days and involved American and British aircraft and U.S. warships. The Pentagon announced that extra aircraft and ground troops were being sent to the area.

Harvard foreign policy experts said they thought the attack will probably not discourage Iraq from developing weapons systems.

I think it's unlikely the bombing campaign will physically slow down his campaign to build weapons of mass destruction", said retired Army Lt. Gen. J. Terry Scott, director of the national security program at the Kennedy School of Government(KSG). "Anything he's got that's vital is deep underground right now".

But others said the U.S. had very few viable alternatives.

Doing something like this may well be the least worst thing", said Francis M. Bator, Littauer professor of political economy emeritus at the KSG and a deputy national security advisor to former President Johnson.

And Scott added that the bombings "will certainly serve notice to [Hussein] that there's...a price to be paid for playing games with the UNSCOM [U.N. Special Commission] inspectors".

Clinton said he acted "to protect the national interest of the United States" and Iraq's neighbors in the Middle East. He gave the go-ahead after consulting with his top advisers and reviewing a U.N. report that said Hussein had again failed to fulfill weapons inspectors.

"Saddam Hussein must not be allowed to threaten his neighbors or the world with nuclear weapons, poison gas or biological weapons", Clinton said. "I have no doubt today that, left unchecked, Saddam Hussein will use these terrible weapons again".

Clinton Cautioned that unintended civilian casualties were a certainty.

Speaking to reporters later, Secretary of State Madeleine K. Albright said the attacks were not designed to "get Saddam Hussein". But she said the United States would step up its contacts with opposition groups and "work with them in a sustained way".

In the charged political atmosphere of the day, Senate Majority Leader Trent Lott (R-Miss.) criticized the military action even before Clinton announced it.

"While I have been assured by administration officials that there is no connection with the impeachment process in the House of Representatives, I cannot support this military action in the Persian Gulf at this time", his statement said.

"Both the timing and the policy are subject to question", he said in a statement.

Asked about Lott's criticism, Defense Secretary William S. Cohen, himself a former Republican senator, said" said: "I am prepared to place 30 years of public service on the line to say the only factor that was important in this decision was what was in the American people's best interests".

Just a month ago, Clinton ordered an attack on Iraq but called it off at the last minute when Hussein promised to cooperate with UNSCOM inspectors.

"Frankly, I would have done it two weeks ago, and the president almost did", said KSG Dean Joseph S. Nye Jr., former assistant secretary of defense under Clinton.

The house had been scheduled to begin debate on four articles of impeachment against Clinton today, with votes likely on Friday, but shortly after the attack began House leaders decided to delay the impeachment debate.

The top two Democrats in Congress voiced their support for the attack. "Saddam Hussein should make no mistake that despite domestic political differences in the United States, the American people and Congress stand firmly behind the defense of our nation's vital interests", Senate Minority Leader Tom Daschle (D-S.D.) and House Minority Leader Dick Gephardt (D-Mo.) said in a statement.

Observers said they agreed with Daschle and Gephardt that the attack was not politically motivated.

Anyone who analyzes the situation realizes the timing was dictated by other events", said Asthenia B. Carter, Ford Foundation professor of science and international affairs at the KSG.

"It's always unbecoming when, as we are putting our servicemen in harm's way, people are making suggestions about why they were sent", he added.

Clinton also alluded to the impeachment debate.

"Saddam Hussein and the other enemies of peace may have thought that the serious debate currently before the House of Representatives would distract Americans, weaken our resolve to face them down", he said. "But once more, the United States has proven that although we are never eager to use force, when we must act in America's vital interests we will do so."

Army Gen. Hugh Shelton, chair of the Joint Chiefs of Staff, said the Pentagon was sending an additional 36 combat aircraft to the Gulf. He said more ground troops also would go.

British Prime Minister Tony Blair, addressing his nation last night, said there was "no realistic alternative to military force.... We act because we must".

Clinton, noting that the holy month of Ramadan starts this weekend, said the airstrikes were necessary now because "for us to initiate military action during Ramadan would be profoundly offensive to the Arab World".

Wire dispatches were used in the compilation of this report.