Pakistani jets bombed militant targets in the main insurgent stronghold along the Afghan border Tuesday in softening-up operations ahead of an expected ground offensive there, authorities said.

The army's resolve to launch the offensive in South Waziristan has deepened after a recent series of bold and deadly militant attacks. The Taliban claimed responsibility Tuesday for a suicide bombing that killed 41 people the previous day elsewhere in the northwest.

The army says 80 percent of the militant attacks in Pakistan are planned from South Waziristan. The United States believes insurgent leaders responsible for the spiraling violence in Afghanistan are also based in the lawless, remote area.

The army and the government have agreed to launch what is expected to be a bloody and difficult ground operation in the mountainous region. An army spokesman Monday declined to say when the offensive would begin and gave no indication it was imminent.

An Associated Press reporter in the town of Dera Ismail Khan, which lies just next to the South Waziristan, reported no unusual movement of military vehicles Tuesday, and did not see large numbers of people fleeing their homes.

For the past three months, jets have been bombing targets in the region, and the military has been trying to cut off militant supply and communication lines. Authorities are also trying to secure the support of militant factions that in the past have agreed not to attack Pakistani troops.

Bombing runs Tuesday destroyed about 15 houses in the Makeen, Ladha and Barwand regions of South Waziristan, a local intelligence official said on condition of anonymity because he was not authorized to brief to the media.

No army spokesman was available to comment. However, the military said in a statement that "terrorists fired 31 rockets" at a convoy of security forces in South Waziristan on Tuesday, wounding two soldiers. It was unclear whether the army bombed the militant targets before or after the rocket attack.

In a reminder of the militants' reach, authorities said helicopter gunship attacks killed 26 insurgents in Bajur, a tribally administered region 185 miles north of Waziristan. The army undertook a major offensive there six months ago and declared it free of insurgents, but some remain.

Abdul Malik, a local government official, said the attacks took place in Damadola and Sawai, known as militant-held areas. He said he got the information about militant casualties from intelligence and military sources.

Pakistan has seen four major terrorist attacks over the last nine days, including a suicide bombing of a U.N. office in the capital, Islamabad, and a 22-hour siege on the army's headquarters.

Pakistan is home to different militant groups that have long had overlapping memberships, among them Al Qaeda fighters from the Middle East and elsewhere in the world, Taliban from the ethnic Pashtun areas of northwest Pakistan and militants from the country's heartland in the Punjab province.

The army says the militants from Punjab joined the Taliban in the weekend attack on the army headquarters, in what appeared to be the latest sign that the various groups were coalescing into a single unit.

Monday's suicide attack occurred in Shangla district next to Swat valley, where the military recently staged out a massive offensive aimed at wiping out a strong contingent of Taliban.

Taliban spokesman Azam Tariq told The Associated Press in a phone call that a wing of the Swat Taliban called the "Farzandan-e-Islam" — or Sons of Islam — carried out the attack and was targeting military vehicles.

"We will continue to attack the army and government," Tariq warned.

He also said that the military's bombings in Waziristan in the past two days have not damaged Taliban sites but rather homes of innocent tribesmen.

Meanwhile, Pakistan's foreign minister was in Washington to lobby U.S. officials to change the terms of a U.S. aid bill that promises the country $1.5 billion a year over the next five years, but also calls on the country to crack down on terrorism and stop the military from interfering in civilian affairs.

Pakistani media reports said Shah Mahmood Qureshi was hoping to get extra language inserted in the bill to allay Pakistani concerns that it was interfering too much in the country's internal affairs before it is signed by President Barack Obama.

The Pakistani army and opposition lawmakers have objected to the bill, driving a wedge between them and the weak civilian government over an aid drive that was supposed to show American support for the country as it battles the insurgents.