Published: May 10, 2010 7:19 PM EDT

ISLAMABAD, Pakistan - U.S. claims that the Pakistani Taliban were behind last week's failed car bombing in Times Square add to pressure on Pakistan's government to attack the militant sanctuary of North Waziristan close to the Afghan border, but few expect its stretched army to rush into any operation there.

New calls from Washington for the army to move into North Waziristan could backfire because they would create the impression the force was acting on the orders of America - a perception that would undercut the public support needed for such an operation to be successful.

Aside from U.S. Secretary of State Hillary Rodham Clinton's warning over the weekend of "severe consequences" if an attack on U.S. soil is traced back to Pakistan, most U.S. officials have been careful not to criticize Pakistan in their public comments since Pakistan-American Faisal Shahzad was arrested soon after the terror attempt in New York.

America is limited in what it can do tackle the threat coming from Pakistan's tribal regions. It is seen as highly unlikely that nuclear-armed Pakistan would ever allow American troops to operate there, meaning Washington must try to work through the Pakistani army, which has received billions of dollars in U.S. aid since 2001.

The Pakistani Taliban, which have previously not conducted attacks on U.S. soil, have been the target of several Pakistani army offensives over the last two years and been battered by scores of American missile strikes. They are allied to al-Qaida, which has also found sanctuary in the northwest, and the Afghan Taliban just across the border.

The army has not moved into North Waziristan, in part because powerful insurgent commanders there have generally not attacked targets in Pakistan. In recent months, however, fleeing fighters and commanders from the Pakistani Taliban - which have launched scores of bloody suicide attacks around the country since 2007 - have moved there.

Even before the failed Times Square bombing, many security analysts had said that the army would need to move into at least some areas of the region if it wanted to deal a decisive blow against militancy in the country.

The army has said it cannot spare the troops for a full-scale offensive this year and needs to consolidate gains elsewhere against militants, including in neighboring South Waziristan. It says it is carrying out small-scale, targeted missions in the north against insurgents, but Associated Press reporters who have visited recently say it is under militant control.

Army spokesman Maj. Gen. Athar Abbas declined to comment on remarks by top U.S. officials over the weekend that Shahzad was working with the Pakistani Taliban. Just last week, Abbas said it was doubtful the group - which has claimed responsibility - could be involved. Asked whether the Times Square incident made a North Waziristan offensive more likely, he said, "Our position is the same as it was in the past."

While U.S. military officials would surely like to see the Pakistani army fighting militants responsible for attacks in Afghanistan as international forces prepare for a new offensive there in the coming months, they have publicly expressed support for arguments advanced by the Pakistan army for holding back for now. In the latest fighting in the border area, nine soldiers and 37 militants were killed Monday in the Orakzai region, where the army has been pressing an offensive for several months, officials said. Two officers were among those killed.

Pakistani defense experts said they believed the army was intent on attacking militants in North Waziristan, but on its own terms. A major operation in North Waziristan would need more troops, likely trigger a major refugee crisis and cost the lives of many soldiers.

"I don't think the timing of this operation will be dictated by American pressure," said Riffat Hussain, professor of defense studies at Quaid-e-Azam University in Islamabad. "You will find an intensification of the search and destroy operations and deepening intelligence coordination to get hold of the people linked to the Pakistani Taliban, especially people who are part of the network that sponsored Faisal Shahzad."

But many analysts agree that even if a ground offensive is launched in the region, it will not target the insurgent network run by Jalaluddin Haqqani, which fights U.S. troops in Afghanistan, or militants loyal to Gul Bahadar, another Afghan-focused commander.

With an increasing focus in Afghanistan on reconciliation with Taliban factions, there is little incentive for Pakistan to fight insurgents who will likely one day form part of the government in the country and be an ally against Indian influence in the region when the Americans withdraw.

"Even if they decide to go in in three or four months' time, they would still avoid those commanders," said Hasan-Askari Rizvi, another defense analyst. "Pakistan has enough enemies already in the tribal areas."