The US has the firepower, but what then for Afghanistan?

British troops feel an understandable hatred when you say this. They’re experiencing record casualties and have done a remarkable job in one of the worst provinces in Afghanistan for five years.

But there’s no getting away from it: they simply can’t do what the Americans can, and they know it.

Today 4,000 Marines are doing what the British have not done for the last few years: pushing deep and forcefully into Taliban territory in Helmand.

It’s not their numbers that make the difference really, but what comes with them. The Americans have the “toys” – the helicopters, the armour, the firepower.

So far their push south into the Helmand valley (I say south – it’s not entirely clear where they’re heading yet, but south would make sense) has met with not that much resistance.

When the Taliban see that coming, they get out of the way. They’ll prefer to take pot-shots at over the next few months.

This doesn’t mean the Americans, with such a mass of explosives, and at times testosterone (although the US Marines are a sensitive bunch), will necessarily do a better job keeping the peace there. But they can push where Britain could not.

I recall talking to a hardworking, stretched and brave British officer in Helmand recently. I asked him if he was ashamed the British were still using the Snatch Land Rover – a lightly covered Jeep that’s been an easy target for Taliban bombs and has permitted many deaths. 

He launched into a passionate defence about how they were light and actually better suited to urban environments. Later I pressed him, and he said: “It’s career suicide to talk out of line here”.

Britain makes do. It does war on the cheap. It borrowed, for example, six Chinooks from the Americans for its recent trumpeted Operation Panther’s Claw, according to one report. It doesn’t have the money the Americans do, but has the ambition.

We want to say we can, and that we did, when sometimes that simply wasn’t the case.

In Helmand, that’s meant that the past two years have seen us slowly walk a careful line between what’s diplomatically called stalemate, and looming failure.

American forces begin a huge offensive today that is aimed at turning that dynamic around. What they will soon find out is whether the ground they re-take has been abandoned by NATO too long for the people to want foreign troops back.