A couple of points: I think it's specifically less about 'having our hand on the spigot' than 'not letting anyone else have their hand on the spigot.' Specifically the Russians (yes, still) or the Chinese or the Indians (or much scarier from my point of view) the Chinese vs. the Indians.
American foreign policy has one and only one strategy, which sits at the top of the pyramid and informs everything that goes on below it. Given the surrounded-by-a-big-ass-moat nature of North American geography, the only thing we have to fear is a united Eurasia -- because only a united Eurasia can muster the resources necessary to make it over the atlantic en masse and attack us directly. (yes, anybody can bomb anybody else, but it doesn't mean shit if you don't follow it up with an invasion -- we (the Americans) have been trying to prove that theory wrong for 60 years now, given the equally arduous task of going someplace across the atlantic to invade another country, but we keep having to send men over. Turns out, an 18-year old from Des Moines sitting in a tank is the best way to convince the locals that the bombing run last week was serious and not something you did on a whim.) This is why the Soviets weren't that big a deal to us in the 20's and 30's, but became a hugefuckingdeal in the 50's after China flipped and they had 4/5s of the landmass and even more of the population.
(if you're wondering about South America, so did James Monroe and John Quincy Adams, which is why they came up with the Monroe Doctrine, the first big expression of the Not In My Backyard school of political thought now so prevalent in America.)
Now, in the year of our lord 2003, we see Russia as the defacto energy supplier to Europe for at least the next 50 years, we see the the fits-and-starts integration of the European Union (though the Iraq show has revealed quite a few cracks, no small number of which we've actively got a crowbar in), that's one big chunk of power coalescing. We see the Chinese growing and growing and running out of room (did you know that the chinese have quietly begun settling in the deep eastern reaches of russia? that's going to be a nasty little fight when it comes). There's another. we see the Indians getting ready to duke it out with the Chinese for strategic influence in Southeast Asia. (They're both building blue-water navies as fast as we or the russians will sell them the ships - and getting ready to have their own little space race.) So we have the big continent clumping up into a few great - maybe even super - powers, and we know from long experience that what great powers do is gang up to go fuck a lesser gang of great powers. Even if it's only economically. So, we can't let it get to that stage, we've got to get our stick in there so that we can keep some leverage on the situation.
As for the international populist movement -- I think you're right about it's potential. I also think it's potential will go almost completely unused in the absence of one specific catalytic component. What's it's missing is Huey Long - or a reasonable simulacrum. It's got no leadership, no galvanizing force that can get it to shut up for a second and move in a coherent direction. (don't get me started on 'Smart Mobs') Right now, this movement can be counted on to successfully 1) show up to protests, 2) protest, and then 3) go eat tempeh and 4) score good weed. To progress beyond that happy but ultimately ineffectual life, we're gonna need someone who can stand up in public and go head to head with the Republicans, call them on their bullshit, propose workable alternatives and ultimately coordinate their removal from power by electoral means. Even leaving aside money on the assumption that there are some monied interests that we can co-opt to fund this thing, I really want to who's gonna step up. Rollover Ralph ain't gonna suffice -- he's got the brains, but this is a pure charisma gig. Huey Long was shot dead in the Capitol Rotunda under mysterious circumstances, and he was a sitting Senator at the time, so I can understand the reluctance to step to the fore. I'd think about it, but I don't particularly want to shave my head and tattoo a target on it. Besides, I have my Secret Plan working. I hope you're right about the critical time being in about two years, because that's when Secret Plan stage 1 gets completed, and it's going to be taking up all my time until then.
A note on Populism...
Populism is the most unpredictable force in American politics. It moves faster than the established power bases can react and therefore has a pretty good lid kept on it. (see the crushing of Jim Hightower as Texas Agriculture Commissioner (by Karl Rove, not coincidentally) in the formative years of my own political education.) It's plays to the stomach and to a sense of fair play and helping out your buddies. It provides the solace of being a part of something larger than yourself. Combine it with patriotism, and you get the Nazis or the dictatorship of Julius Caesar -- deplorable certainly, but able to make big changes in a hurry. It's got the horsepower we need, the question is: who's hand are we gonna put on the wheel?