Shame on Sens. Edward Kennedy (D-Mass.) and Robert Byrd (D-W.Va.) for picking a moment of high danger for U.S. troops in Iraq to declare, in essence, that their activities are in vain.

And shame, too, on former New Jersey Gov. Thomas Kean (R), chairman of the Sept. 11, 2001, investigating commission, for issuing a prejudgment that the terrorist attacks that day could have been prevented. [IMGCAP(1)]

At the same time, kudos are in order for Sen. John McCain (R-Ariz.), who countered the Kennedy-Byrd claim that Iraq is “another Vietnam” and to National Security Adviser Condoleezza Rice, who candidly explained that, to have prevented 9/11, the whole culture of the U.S. government would have had to be different.

Kennedy and Byrd have often and vociferously expressed their opposition to President Bush’s Iraq policy. History may prove them right.

But it’s unconscionable for two senior Senators to declare, amid the most serious combat that U.S. troops have faced in months, that they are engaged in, in Kennedy’s words, “a quagmire” — i.e., a war that America should be pulling out of.

Before someone claims I’m impugning their patriotism — it’s standard practice for Democrats to claim their loyalty is being questioned — I’m not. I’m questioning their timing, their discretion and their good judgment.

Both of them seem to hate Bush so much that they couldn’t restrain themselves from comments that, when broadcast to the Middle East, could only demoralize U.S. troops and embolden Iraqi insurgents.

Kennedy first used the line that “Iraq is George Bush’s Vietnam” as part of a vitriolic speech last Monday at the Brookings Institution in which he accused Bush of lies, smears, despicable cynicism, of undermining national security, the economy and “our very democracy.”

He’s entitled to his opinion, although it’s doubtful that his colleague Sen. John Kerry’s (D-Mass) presidential campaign is helped by having America’s most identifiable liberal as his chief attack dog.

Kennedy certainly can energize the Democratic base, but he’s equally sure to energize Bush’s, and he persuades no independents, swing voters or moderates whatsoever.

Kennedy didn’t stop with merely equating Iraq and Vietnam. On April 7, with U.S. troops furiously fighting both Saddamist insurgents in Fallujah and Ramadi and radical Shiite thugs elsewhere, he expanded on the point.

While expressing “enormous admiration” and “whole-hearted support” for the troops, he said, “Vietnam ended up in a quagmire, Iraq is ending up a quagmire. … We need a new start in Iraq [to] bring our troops home safely.”

Kennedy didn’t fully spell out the logic of his argument: If you’re in “another Vietnam,” you pull out. Byrd did so, however. “Pouring more U.S. troops into Iraq is not the path to extricate ourselves,” he said.

He advised internationalizing the Iraqi occupation to “take U.S. soldiers out of the cross-hairs of angry Iraqis.” This may be a wise policy, but why express it when U.S. soldiers are directly in the cross hairs? The implication is that Americans should stop fighting.

Prompted or not, America’s new sworn enemy, Shiite firebrand Muqtada Al Sadr, picked up on the theme, calling on the American people to align with him or “Iraq will be another Vietnam for America.”

Fortunately, McCain responded to Byrd, “I happen to know something about Vietnam, and I know that we do not face another Vietnam.”

He made the points that Iraqi insurgents have no superpower backing or off-limits sanctuaries, as North Vietnam had, and that the enemy is a fraction of the Iraqi population, not the whole.

He didn’t add, but might have, that Bush does not face a Democratic-dominated Congress, which turned hard against the Vietnam War once Republican Richard Nixon became president and ultimately pulled the rug out from under South Vietnam.

“If we fail, if we cut and run, the results can be disastrous,” McCain said. There will be “a fragmentation of Iraq … [and] an unchecked hotbed of training ground for individuals who are committed to the destruction of the United States.” Amen.

Meantime, Kean said on NBC’s “Meet the Press” on April 4 that “the whole story [of 9/11] might have been different” if intelligence and law enforcement blunders hadn’t occurred beforehand. That may be right, but it’s a conclusion to be drawn by his entire commission, not the chairman.

Kean’s comment was put in correct perspective by his co-chairman, former Rep. Lee Hamilton (D-Ind.), who said, “You can string together a whole bunch of ifs, if things had broken right in all kinds of different ways … and, frankly, if you’d had a little luck, it probably could have been prevented.”

Leading Democrats, including Kerry, have kept clear of blaming the Bush administration for 9/11, but in flurries of e-mail traffic the supposedly nonpartisan Center for American Progress and emphatically partisan America Coming Together have charged that Bush had sufficient warning to have prevented the attacks.

Rice countered effectively, admitting that neither the Clinton nor the Bush administration had adequately altered the government’s intelligence and law enforcement structures to deal with the threat of attacks inside the United States.

One can only imagine the howls that would have arisen from civil libertarians and Democrats if, say in March 2001, Attorney General John Ashcroft had recommended that the CIA and FBI begin sharing intelligence and that Congress pass the USA Patriot Act.

And, can anyone believe that Congress would have authorized an invasion of Afghanistan before 9/11, even if such a thing had been possible?

It’s clear from commission staff reports and public testimony — even that of Rice nemesis Richard Clarke — that neither the Clinton nor the Bush administration took adequate steps to deal with the al Qaeda threat.

Rice testified that what Bush is doing now in Iraq is an attempt to deal with the root causes of that threat: the lack of democracy and opportunity in the Middle East. The United States is trying to build a model in Iraq.

It may not work. If it doesn’t, those who opposed the effort will succeed politically and Bush will fail. But in the midst of serious combat, responsible Americans shouldn’t say things that will help the enemy.