Anti-American feeling is strong in Kashmir
Pakistani militants have been crossing into Afghanistan since the start of the US-led military campaign, vowing to defend the Taleban regime and Osama Bin Laden.
The issue came to the fore when one group, the Harkat-ul-Mujahideen, reported that at least 22 of its members were killed in a US air strike on Kabul on Tuesday, and Pakistan tried to obstruct the return of their bodies.
The Afghan opposition has long accused the Taleban of having Pakistani troops in its ranks - an allegation rejected by Pakistan.
But it does appear that a growing number of young Pakistani Muslims who might otherwise have gone to fight India in Kashmir are now volunteering to fight for the Taleban.
Kashmiri link
Harkat-ul-Mujahideen, for one, normally operates in Kashmir, and links between Afghanistan and armed groups in Kashmir date back to the early 1980s, before the Taleban emerged.
Prominent Kashmiri militants such as Mohammad Abdullah Bangroo, alias Khalid-ul-Islam, fought alongside the Afghan mujahideen against the Soviet occupation.
Likewise, an Afghan militant in the Hizbul Mujahideen group, Akber Bhai, became a household name in north Kashmir in 1992.
Afghan militants who fight in Kashmir are only one foreign contingent among many but for those involved - be they from Pakistan, Saudi Arabia, Turkey or Chechnya - Kashmir and the Afghan cause are strongly linked as common Islamic causes.
If casualty figures are any indication, foreigners comprise about 30% of the militants operating in Kashmir, most of them Pakistanis or from Pakistan-ruled Kashmir. They are followed by the Afghans.
It has to be said that before the 11 September attacks on America, there was no clear indication of links between Kashmiri militants and the Taleban or Osama Bin Laden's al-Qaeda militant group.
But since the US strikes in Afghanistan, Bin Laden has become a hero to ordinary Muslims in Kashmir. There he is seen as a symbol of Islamic resistance to a United States which is involved in conflicts between Muslims and non-Muslims such as the Middle East.
Pakistani volunteers
In Pakistan's western regions, the Taleban cause is replacing Kashmir as the issue of the day in teashops.
Young men from the Pakistani border areas often went off to what they called a Muslim holy war in Afghanistan during the Soviet occupation.
Pashtun people in the region, or Pathans as they are often known in Pakistan, are ethnically the same as Afghan Pashtuns, who make up the Taleban's main support.
Many Pashtuns do not recognise the border and young men in Pakistan have regularly gone off to fight for the Taleban Afghanistan's civil war for a few weeks or months - often during their summer holidays.
Taleban supporters in western Pakistan have been holding rallies at which many have signed up for what they consider a new holy war against the US, and observers in Peshawar say perhaps several hundred have actually gone over in recent weeks.
One new development is that many non-Pashtun Pakistanis are now joining the rush to Afghanistan - Punjabis and Sindhis from eastern provinces who are traditionally less militant.
There are perhaps a few thousand Pakistanis now fighting in Afghanistan although no one knows the true number.