Yemen's anti-terror unit is now under pressure to get results
An al-Qaeda group in Yemen was behind the failed attempt to blow up a US aeroplane on Christmas Day, according to US intelligence officials. Jeremy Bowen has been to Yemen to investigate the growth of al-Qaeda.
When Donald Rumsfeld was the American secretary of defence, you may remember he used to talk about known unknowns and unknown unknowns.
Well, for me Yemen was an unknown unknown. After years in the Middle East, Jerusalem, one of the world's most compelling cities, feels about as familiar and un-exotic as south London. Beirut, Damascus and a few other places are not far behind.
But this was my first visit to Yemen. To be honest, I had forgotten what it was like to come to a new country, especially one where not everybody can be counted on to be friendly all of the time.
When I got on the plane, I had a hint of that gnawing feeling I used to get when I started going to places the Foreign Office would tell you to avoid.
After a night of travelling, I fell asleep looking out of the plane window as the sun was rising over Dubai. I had been trying to spot where in the skyscraper forest the world's new tallest building was piercing the pink haze.
I woke up looking down on Yemen, on rugged, jagged mountains, deep valleys and, very occasionally, little houses looking like beehives wedged into the cliffs.
President Saleh's government has been accused of being ineffective
Dubai is so of its time that it is almost a caricature of the modern world.
Yemen is what the Middle East used to be for travellers from Europe - remote, traditional, deeply unfamiliar and, when you have not been there, a little bit scary.
Yemen has some charming people, who like a joke. You do not find that everywhere in the Middle East.
They like chewing khat - the leaf which is a mild stimulant - too. Every afternoon many men have one bulging hamster cheek, little green fronds of khat cud poking out of their lips as they masticate.
The other day our driver and government minder were happily chewing away, mellow in their work, chuckling every now and then as the BBC jeep chugged about its business.
Most countries would consider themselves to be in crisis if they had just one of Yemen's afflictions.
Yemen has the lot: tribal war, separatists, poverty, and now al-Qaeda - a problem here for the last few years, even though it has only been in the headlines for the last few weeks.
Heavy handed American military intervention is al-Qaeda's dream - it would turn the whole country against the West and make President Obama their recruiter-in-chief
Yemen has many more guns than people. One analyst quipped: "We don't need US military aid. We could export guns to them."
One day our car was parked in a narrow street on the edge of the stunningly beautiful old city of Sanaa.
Its buildings are tall and elegant, sculpted from mud bricks with windows like jewels.
I could not get back to the car door because a group of young men, dressed like many here in robes held together by an ornate belt and a curved knife, were squatting down on the pavement, counting out brand new bullets.
A few notes changed hands, and the bullet seller got up and grinned like a boy on his birthday.
He was an off-duty soldier, and he mimed bringing his gun, presumably now empty, to attention on his shoulder.
I have heard stories here of much more powerful men selling the Yemeni navy's diesel to African go-betweens. A corrupt government is another problem to add to the list.
If the Americans were designing an ally, they would not come up with Yemen. But Yemen is the ally they have, and for now the Americans appear to be happy with the regime's response to al-Qaeda over the last few months.
But that might not last. The local franchise, al-Qaeda in the Arabian Peninsula, apparently tried to blow up a plane over an American city, so the superpower is not going to let this one go.
Comparisons with Afghanistan are tempting but premature. Yemen is not a failed state. But it is failing, and if this emergency is mishandled it might be the breaking point.
Heavy-handed American military intervention is al-Qaeda's dream. It would turn the whole country against the West and make President Obama their recruiter-in-chief.
I think the Americans realise that.
One night I ate in the market with the British ambassador and a few of his friends in a raucous and scruffy cafe. We had magnificent fresh fish cooked in ovens like volcanoes, tipped onto the tables and eaten with fingers and bread.
Everyone was friendly, and we dined like kings.
But the ambassador's bodyguards were there, too, they had to be, and in a few serious moments we talked about the British engineer and a German family with young children who are missing, kidnapped in the north.
Yemenis are not always so delightful.
Many people here have told me that the only way forward is to rebuild Yemen so that its people will not be seduced by the jihadists' violent vision of a glorious martyr's death.
That will take time. You can choose, someone said - quick results or good results. Not both.
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