Under the gun: a US strike in Afghanistan would anger militants in Pakistan
The anti-American protests in Pakistan - which are expected to grow if the US retaliates against Afghanistan for the September 11 attacks in New York and Washington - have been led by Pakistan's religious parties.
Like Israel, Pakistan was created as a religious safe haven - a homeland for the Muslims of the Indian sub-continent.
Support on the streets
Yet religious parties have never managed to win more than five per cent of the vote in an election.
But they can mobilise their supporters on the streets, political analysts say.
"They are important in terms of ... their ability to manifest their strength in the street, their ability to mobilise their cadres in educational institutions, within the armed forces and now, increasingly, through their militant cadres," said political analyst Hussain Haqqani.
Pakistan has at least 33 religious parties, but only two have any real political significance.
One is the Jamiat Ulema Islam (JUI), which maintains close links with the Taleban in Afghanistan. Both groups follow the Deoband school of Islam, created soon after the 1857 mutiny against the British colonial authorities.
'Back-to-basics' Islam
"The Deobandi mindset refuses to recognise the validity or usefulness of anything western and anything that is not essentially in the Islamic tradition," Mr Haqqani said.
Both the JUI and the Taleban are dominated by Pashtuns, an ethnic group which straddles the Pakistani-Afghan border.
But Pakistan's other major religious party, the Jamaat-e-Islami, is spread throughout the country.
Theology also divides the two parties. Jamaat is close to Wahhabism, the kind of Islam practised in Saudi Arabia.
The party, which has close ties with the Muslim Brotherhood, wants to purify and revive Islam.
"It is essentially a group of activists who want to see Islam translated in economy, in political life, in terms of basic human values, not in terms of theology," said Dr Anees Ahmad of the International Islamic University.
Dr Ahmad said Jamaat was the only religious party in Pakistan that has shown itself to be open and friendly with the west.
"They realise the west has a number of traditions which are our own," he said.
Unity under attack
The distinctions and tensions between Pakistan's different religious parties tend to melt away in the face of any threat to Islam.
Both the Jamaat-e-Islami and the JUI have allied themselves with a dozen smaller religious parties this year to form the Afghan Defence Committee, which has sworn to defend the Taleban.
But will ordinary Pakistanis back the religious right if the United States launches a major military action against Afghanistan?
"Pakistani nationalism is rooted in Islam," says Hameed Gul, a former head of Pakistan's military intelligence agency, the ISI,
"There are 225,000 mosques in the country and from each pulpit when the call goes up - let's say of jihad [holy war] - you see no political party has such a wide infrastructure," General Gul said.
"In the villages and everywhere those people can be mobilised. They would not be mobilised in the name of politics, but they can be mobilised in the name of religion anytime."
General Gul said that if Kabul came under attack and called for jihad, many would be prepared to take up arms.
That would depend partly on how prolonged and how bloody any US military action turns out to be.
But it is certain that if and when the attack comes, Pakistan's religious parties will sink their differences and take their supporters and their armed activists out on to the streets.