Prime Minister Tony Blair and Joint Chief of Defense Staff Sir Charles Guthrie (AP)

LONDON, Dec. 19—Prime Minister Tony Blair said tonight that four days of Operation Desert Fox caused "substantial damage" to air bases, missile factories, support systems for chemical and biological warfare, and bases of the special Republican Guard in Iraq.

"Our objectives have been achieved," Blair declared when he announced here -- simultaneously with President Clinton's similar announcement in Washington -- that the current round of airstrikes had been brought to an end. "We can be satisfied with a job well done."

Standing before a brightly lit Christmas tree outside No. 10 Downing St., Blair said, "We set out to diminish and degrade Saddam's military capability, and we have done so." He added, "We regret any civilian casualties."

Blair did not provide details of the targets damaged in Iraq, but he said "tonight, significant parts of Iraqi President Saddam Hussein's military infrastructure are in ruins. . . . There has been real damage to the special Republican Guard units."

The fairly quick end to the operation, and the claims of success, should mean that Blair will continue to receive the strong backing on Iraq that he has reaped from the media and even from opposition political parties since the new round of airstrikes began on Wednesday.

"We'll bomb into Ramadan," read the headline in Britain's largest broad-sheet newspaper today.

And the most widely read newspaper, the News of the World, with 10 million readers each Sunday, reveled in the war in its early editions. "Ramadan Busters: Holy Feast Fails to Stop RAF," read the banner front-page headline.

There are 11 daily newspapers here in the British capital, and they rarely agree on news or views.

But the past week has produced a burst of unanimity in the British media, with almost every newspaper and broadcast outlet offering broad support for the latest round of airstrikes on Iraq and Britain's role in it. The political world has been equally strong in backing the resort to firepower.

There was broad approval after the initial U.S. raids on Iraq early Thursday. Then, when Royal Air Force Tornado bombers based in Kuwait began missions of their own later in the day, the nation erupted in a patriotic burst of pride.

When Blair stood up in the House of Commons Thursday afternoon to announce that "British Tornados are in the air above Iraq," the members broke into cheers. And the participation of the home team made the media reaction to Operation Desert Fox even more positive.

The London tabloids, displaying their uncanny penchant for reducing complex global developments to a single syllable, ran color pictures of damaged Iraqi cities under headlines a half-page tall that read "Blitzed!" and "Doomed!"

"Our boys blast the butcher of Baghdad!" ran a headline in the Daily Mirror. The broad-sheet newspapers said essentially the same thing, in slightly more measured language.

So far, even the traditionally liberal papers have been supporting the air raids. The tone on the left was reflected in an editorial in the Independent. "The attacks launched by Britain and America will probably go down as the futile end of a futile policy," the paper's lead editorial said on Friday. "And yet, at this stage, Washington and London had no alternative. . . . If anything, the allies should have gone ahead with the attack that was called off at the last moment on 14 November."

That was essentially the position that Blair took as well. "This is not a cause of celebration," Blair said in Parliament. "This is a terrible thing we have to do, a grim necessity."

Thursday's hour-long debate in the House of Commons turned into a parade of politicians backing the air raids. "The prime minister has our full support," said William Hague, leader of the chief opposition party, the Conservatives. The third-largest party, the Liberal Democrats, chimed in to agree.

The only dissent came from a few members of the liberal wing of Blair's Labor Party. A Labor legislator from Scotland, George Galloway, said the attack would bring condemnation from "the one-thousand-million-strong Muslim community around the world."

Still, nobody here has failed to remark on the coincidence of timing between the latest military sortie and the impeachment vote in the House of Representatives. But the charge that Clinton attacked Saddam Hussein to reduce the pressure on himself has not caught on here.

This may be because Blair has argued that the decision to strike "had no relationship whatsoever to domestic events in the U.S."