By Frank Gardner BBC security correspondent

The very grievances that drive some passionate young Muslims to sacrifice their lives to hurt US interests have not gone away. If anything, they have increased in number

One of its most valuable operatives, Ramzi Binalshibh, has been captured alive in Karachi, and 10 other suspects have been caught with him.

In upstate New York the FBI has announced it has caught a suspected sleeper cell.

And in south-east Asia, two dozen Islamist militants with suspected links to al-Qaeda have been arrested in Singapore and the Philippines.

The shadowy organisation of Osama Bin Laden is clearly taking casualties.

Huge blow

The arrest of Ramzi Binalshibh is al-Qaeda's most spectacular setback since the collapse of the Taleban rule.

Binalshibh's capture is thought to be a huge blow for al-Qaeda

Although some in the organisation are insisting he is still at large, the Americans are certain they have got him and they are wasting no time.

He was caught in Pakistan on 11 September, and already he has been spirited out of the country.

At this very moment he is likely to be answering some probing questions at a secret US facility, possibly in Afghanistan, possibly onboard a warship in the Arabian Sea.

Only a few days ago Mr Binalshibh appeared to be boasting to the Arabic satellite channel al-Jazeera that had played a major, co-ordinating role in the 11 September attacks.

Now his US interrogators will be encouraging him to enlighten them further on that role and who else was involved.

Interestingly, Mr Binalshibh is being isolated from other suspected al-Qaeda prisoners, and - like other key captives - he is not being sent to Guantanamo Bay.

Instead he is being detained in a part of the world where interrogators have habitually paid scant attention to human rights.

'Truly global network'

Elsewhere, the capture of cells thought to be linked to al-Qaeda are relatively minor blows from which the organisation can doubtless recover.

Arab leaders fear backlash from public Arab opinion

If anything, they are an uncomfortable reminder that al-Qaeda is truly a global network with supporters as far apart as the jungles of south-east Asia and the rural heartland of America.

And herein lies the problem.

The US and its allies are now at last making some progress in confronting al-Qaeda.

But while they notch up the tally of who they have caught and who they have killed, they are doing little to address a more profound problem.

The very grievances that drive some passionate young Muslims to sacrifice their lives to hurt US interests have not gone away. If anything, they have increased in number.

Muslim outrage

In the Palestinian territories, in Afghanistan, in Iraq, and in Yemen, US policy is seen by many Muslims - often unfairly - as being "anti-Islamic".

Many have come to see the Afghan campaign of last autumn not as a liberation from oppressive Taleban rule, but as an intentional bombing campaign that targeted women and children.

Washington's sabre-rattling over Iraq is making many Arabs talk of a US-imposed new world order in the Middle East whereby puppet regimes will all supposedly dance to America's tune.

And in the core conflict of the region, Washington's unstinting support for the Arab world's "bete noir" - Israeli Prime Minister Ariel Sharon - may yet replenish al-Qaeda's depleted ranks.