John McCain sure knows how to say bon voyage. 

With Barack Obama packing his bags for next week's journey to Europe and the Middle East--where the entire U.S. political press corps will watch, dumbstruck, as hope and change and audaciousness spread unbridled o'er the land--the Arizona Republican this afternoon gave his rival a not-so-friendly parting gift: the first real negative ad of the 2008 general-election cycle. Called "Troop Funding," the blistering spot uses the Democrat's overseas trip to compare him unfavorably to McCain on national security and press the case that he's a no-good, yellow-bellied, flip-flopping opportunist.

The only problem: it doesn't make a whole lot of sense.

The ad accuses Obama of three offenses: he "never held a single Senate hearing on Afghanistan," even though he chairs the Senate foreign relations subcommittee tasked with overseeing military operations in that country; he "hasn't been to Iraq in years"; and he "vot[ed] against funding our troops." All of these, says an announcer, are "positions that helped him win his nomination"--and now that he has, "he's changing to help himself become president." So what's wrong here? For starters, none of these "positions" actually helped Obama win the Democratic nod. It's not like the party was looking for a troop-hating, Iraq-avoiding, hearing-skipping candidate and Obama happened to fit the bill. So the whole "he's changing to help himself" accusation isn't particularly convincing.

More importantly, while the individual complaints may sound damning when simplified and strung together, they quickly crumble upon closer examination--especially as contrasts with McCain. It's true that Obama never held a single Senate hearing on Afghanistan--but that's because Joe Biden, the chairman of the Foreign Relations committee, has insisted that hearings on this critical issue be held at the full committee level, and not at the subcommittee level. It's also true that Obama has only attended on Afghanistan-related Senate meeting over the past two years, as McCain has loudly noted elsewhere. Unfortunately, McCain's record--he's attended zero of his Armed Services committee's six hearings on the subject since 2006--is even worse. Sadly, that's what happens when you're running for president--the day job suffers. Neither Obama nor McCain should treat his opponent's Capitol Hill absences as especially unusual. Nor should voters.

Then there's the little issue of "vot[ing] against funding our troops." Sounds despicable, right? Unfortunately, it's just another example of the way Washington works. Obama did, in fact, vote against a 2007 war-funding bill. But it wasn't because he hates American soldiers. Instead, he was registering an objection to legislation that "lacked a timetable for troop withdrawal"--a position that arguably means he was more concerned about troop well-being, not less. Reasonable people can disagree over whether timetables are warranted. But portraying this as a vote "against the troops" is silly. It's also a game two can play. On March 29, 2007, McCain voted against H.R. 1591, an emergency spending bill designed to fund the wars in Afghanistan and Iraq and provide more than $1 billion to the Department of Veterans Affairs. Why? Because it included a timetable for troop withdrawal. Does than make him a anti-soldier? Not at all. But it wouldn't stop an opponent from characterizing his vote--unfairly--as such.

Finally, there's Iraq. This is probably McCain's most meaningful beef with Obama. Since May, the Arizonan, who visits every few months, has said that his rival, who hasn't visited since 2006, should return and assess the changing conditions in person. He's right. As my NEWSWEEK colleague Michael Hirsh noted earlier today, "the Democratic senator missed witnessing the sectarian violence that roiled Iraq for more a year, and he has not had a firsthand look at the surge's success even as he has continued to say he would withdraw troops within 16 months of his presidency." But there are two important caveats to consider. One, heavily chaperoned congressional travel doesn't always offer the most accurate (or revealing) view of a war zone. Take McCain's April 1, 2007 trip to Baghdad. At the time, McCain claimed that his stroll through an open-air market proved that people could now "walk freely" through the city. But it was later reported that the candidate wore a flak jacket and received protection from 100 soldiers, three Blackhawk helicopters and two Apache gunships during his promenade; snipers returned the next day and murdered a few Shiite merchants. (CNN even deemed the area too dangerous to visit without military escort.) Second, Obama is already planning do this summer what McCain has said he should do--that is, visit Iraq. This doesn't change the fact that he should've gone earlier. But it does instantly outdate the Republican's attack.

Ultimately, McCain is trying to frame Obama as a no* know-nothing foreign-policy novice maneuvering for maximum political gain. He may have a point. He may not. But by choosing to focus "Troop Funding" on matters of symbolism rather than substance, he doesn't really make it.

*D'oh.