ISLAMABAD, Pakistan — Pakistan began moving thousands of troops from the Afghan border toward India, officials and witnesses said Friday, raising tensions between the nuclear-armed neighbors and possibly undermining the U.S.-backed campaign against al-Qaida and the Taliban.
The country also announced that it was canceling all military leave in the aftermath of last month's terror attack on the Indian financial capital of Mumbai.
India has blamed Pakistani militants for the terrifying three-day siege; Pakistan has demanded that India back this up with better evidence.
Pakistan's latest moves were seen as a warning that it would retaliate if India launches air or missile strikes against militant targets on Pakistani soil _ rather than as an indication that a fourth war was imminent between the two countries.
The United States has been trying to ease the burgeoning crisis while also pressing Pakistan to crack down on militants Washington says were likely responsible for the Mumbai attack. The siege left 164 people dead after gunmen targeted 10 sites including two five-star hotels and a Jewish center.
On Friday, U.S. intelligence and military officials were trying to determine if the reported troop movements were true and _ if so _ what Pakistan's intent might be.
They cautioned that the reports may be exaggerated, aimed more at delivering a message than dispatching forces. The officials spoke on condition of anonymity to discuss intelligence matters.
Any significant troop movement would likely dash President-elect Barack Obama's strategy of having Pakistan concentrate on the threat emanating from the lawless tribal regions close to Afghanistan, where Osama bin Laden and other al-Qaida leaders are believed hiding out.
Obama said nothing publicly about the Pakistan situation Friday.
"This is a serious blow to the war on terror in the sense that the whole focus is now shifting toward the eastern border," said Talat Masood, a former general and military analyst. "It will give more leeway to the militants and increased space to operate."
Two Pakistani intelligence officials said Friday that elements of the army's 14th Infantry Division were being redeployed from the militant hotspot of Waziristan to the towns of Kasur and Sialkot, close to the Indian border.
The military began the troop movement Thursday and plans to shift a total of 20,000 soldiers _ about one-fifth of the deployment in the tribal areas, they said without providing a timeframe.
The officials spoke on condition of anonymity because of the sensitivity of the situation.
An Associated Press reporter in the Dera Ismail Khan district and a witness thirty miles away in Bhakkar, a district bordering Waziristan, saw long lines of military vehicles carrying hundreds of soldiers and equipment away from the Afghan border toward India.
"It was a big, big convoy," said Mushtaq Bokhari, a resident of Bhakkar district in Punjab province close to the border with Pakistan's North West Frontier Province. "It took about three hours to pass through our city."
However, a senior Pakistani security official denied that the troops were being deployed to the Indian border.
He said a "limited number" of soldiers were being shifted from areas "where they were not engaged in any operations on the western border or from areas which were snowbound."
He declined further comment and asked that his name not be used, also citing the sensitivity of the situation.
Pakistan and India have fought three wars since their independence from Britain in 1947, two over Kashmir, a majority Muslim region in the Himalayas claimed by both countries.
They came close to a fourth after suspected Pakistani militants attacked India's parliament in 2001. Both countries deployed hundreds of thousands of troops to the disputed Kashmir region, but tensions cooled after intensive U.S. diplomacy.
India and Pakistan have said they want to avoid military conflict over the Mumbai attacks, and most analysts say war is unlikely, not least because both sides have too much to lose if conflict breaks out.
But India _ which is under domestic pressure to respond forcefully _ has not ruled out the use of force. And Pakistan has promised to respond aggressively to any strike on its soil.
Even as reports emerged Friday about a major redeployment, Pakistani Prime Minister Syed Yousuf Raza Gilani and other top government officials Friday sought to reduce tensions.
"We will not take any action on our own," Gilani told reporters. "There will be no aggression from our side."
Indian Foreign Minister Pranab Mukherjee accused Pakistan of trying to divert attention away from what many analysts say is a halfhearted attempt to rein in homegrown terror groups like Lashkar-e-Taiba, which India accuses of masterminding the Mumbai attacks.
"They should concentrate on the real issue: how to fight against terrorists and how to fight against and bring to book the perpetrators of Bombay terrorist attack," he said.
Pakistan says it has arrested several senior Lashkar members and cracked down on a charity the U.S. and the U.N. say was a front for Lashkar.
U.S. and Indian officials say Pakistan's powerful intelligence agencies created Lashkar and other militant groups in the 1980s by to battle Indian-rule in Kashmir.
While they have been careful not to accuse Pakistani state agencies in the Mumbai attacks, there are doubts that the young civilian government of President Asif Ali Zardari is strong enough to persuade the security forces to move decisively against the militants.
Pakistan has promised to cooperate with India in any probe but says it needs to see evidence before it can investigate any further. Mukherjee said Friday that India had provided more than enough evidence about the militants, who infiltrated Mumbai by sea.
"We have indicated to them that there are ample evidences from the log book of the captured ship, from the information available from satellite telephones and various others that elements from Pakistan were responsible for this attack," Mukherjee told reporters.
Pakistan has deployed more than 100,000 of its 600,000-strong army in Waziristan and other northwestern regions to fight Islamic militants blamed for surging violence against Western troops in Afghanistan as well as suicide attacks in Pakistan.
Security officials have previously said the country would be forced to withdraw troops from the Afghan border if tensions with India _ whose army is twice as large _ escalated.
Many of the country's remaining troops are believed to be based close to the Indian border already, a legacy of the countries' history of conflict.
C. Uday Bhaskar, former director of India's Institute of Defense Studies and Analyses, said he saw the troop movement as "more to do with a signal to the Americans _ don't push us too hard.
"I think there's posturing within Pakistan to say, 'No one can push us around, not the Americans, not the Indians,'" he said.
Associated Press reporters Sebastian Abbot, Asif Shahzad and Zarar Khan in Islamabad, Sam Dolnick in New Delhi and Lolita C. Baldor in Washington contributed to this report.