Hello and welcome to the Intelligence on Economist Radio. I'm your host, Jason Palmer.

Every weekday, we provide a fresh perspective on the events shaping your world.

Much of the attention on climate change has focused on carbon dioxide,

but a far more potent molecule plays a big role too, methane.

Reducing many sources of it would be easy, and plugging the many leaks of the stuff would actually save money.

And the mountainous kingdom of Bhutan, sandwiched between India and China,

seems like a tricky place to distribute vaccines.

But thanks to its science-minded leadership and advice from some monks,

it's had a world-beating vaccination drive.

First up, though, nearly 20 years since American forces entered Afghanistan, President Joe Biden has announced the withdrawal of all troops from the country.

I'm now the fourth United States president to preside over American troop presence

in Afghanistan.

I will not pass this responsibility onto a fifth.

I've concluded that it's time to end America's longest war.

It's time for American troops to come home.

The pullout will coincide with the anniversary of the September 11, 2001, terror attacks

that prompted the American invasion.

We witnessed one of several U.S. airstrikes just behind the Taliban front lines.

Targets apparently included artillery and anti-aircraft units.

A decade ago, at the height of the ensuing war,

there were 100,000 American troops in the country.

Now there are around 2.5,000.

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