ISLAMABAD, Pakistan - Steps by the United States to vastly expand its aid to Pakistan, as well as the footprint of its embassy and private security contractors here, are aggravating an already volatile anti-American mood as Washington pushes for greater action by the government against the Taliban.

Supporters of the Islamic party Jamaat-e-Islami rallied in August against plans to expand the American embassy in Islamabad. (B. K. Bangash/Associated Press) An aid package of $1.5 billion a year for the next five years passed by Congress last week asks Pakistan to cease supporting terrorist groups on its soil and to ensure that the military does not interfere with civilian politics. President Asif Ali Zardari, whose association with the United States has added to his unpopularity, agreed to the stipulations in the aid package.

But many here, especially in the powerful army, object to the conditions as interference in Pakistan's internal affairs, and they are interpreting the larger American footprint in more sinister ways.

American officials say the embassy and its security presence must expand in order to monitor how the new money is spent. They also have real security concerns, which were underscored Monday when a suicide bomber, dressed in the uniform of a Pakistani security force, killed five people at a United Nations office in the heart of Islamabad, the capital.

The United States Embassy has publicized plans for a vast new building in Islamabad for about 1,000 people, with security for some diplomats provided through a Washington-based private contracting company, DynCorp.

The embassy setup, with American demands for importing more armored vehicles, is a significant expansion over the last 15 years. It comes at a time of intense discussion in Washington over whether to widen American operations and aid to Pakistan - a base for Al Qaeda - as an alternative to deeper American involvement in Afghanistan with the addition of more forces.

The fierce opposition here is revealing deep strains in the alliance. Even at its current levels, the American presence was fueling a sense of occupation among Pakistani politicians and security officials, said several Pakistani officials, who did not want to be named for fear of antagonizing the United States. The United States was now seen as behaving in Pakistan much as it did in Iraq and Afghanistan, they said.

In particular, the Pakistani military and the intelligence agencies are concerned that DynCorp is being used by Washington to develop a parallel network of security and intelligence personnel within Pakistan, officials and politicians close to the army said.

The concerns are serious enough that last month a local company hired by DynCorp to provide Pakistani men to be trained as security guards for American diplomats was raided by the Islamabad police. The owner of the company, the Inter-Risk Security Company, Capt. Syed Ali Ja Zaidi, was later arrested.

The action against Inter-Risk, apparently intended to cripple the DynCorp program, was taken on orders from the senior levels of the Pakistani government, said an official familiar with the raid, who was not authorized to speak on the record.

The entire workings of DynCorp within Pakistan are now under review by the Pakistani government, said a senior government official directly involved with the Americans, who spoke candidly on condition of anonymity.

The tensions are erupting as the United States is pressing Pakistan to take on not only those Taliban groups that have threatened the government, but also the Taliban leadership that uses Pakistan as a base to organize and conduct their insurgency against American forces in Afghanistan.

In a public statement, the American ambassador, Anne W. Patterson, suggested last week that Pakistan should eliminate the Afghan Taliban leader, Mullah Omar, a onetime ally of the Pakistanis who Washington says is now based in Baluchistan, a province on the Afghanistan border. If Pakistan did not get rid of Mullah Omar, the United States would, she suggested.

Reinforcing the ambassador, the national security adviser, Gen. James L. Jones, said Sunday that the United States regarded tackling Qaeda sanctuaries in Pakistan as "the next step" in the conflict in Afghanistan.

The Pakistani army chief, Gen. Ashfaq Parvez Kayani, in an unusually stern reaction last week, said that missile attacks by American drones in Baluchistan, as implied by the Americans, "would not be allowed."

The Pakistanis also complain that they are not being sufficiently consulted over the pending White House decision on whether to send more troops to Afghanistan.

The head of Pakistan's chief spy agency, the Inter-Services Intelligence directorate, or ISI, Lt. Gen. Ahmed Shuja Pasha, met with senior officials at the Central Intelligence Agency last week in Washington, where he argued against sending more troops to Afghanistan, a Pakistani official familiar with the visit said.

The Pakistani Army, riding high after its campaign to wrench back control of the Swat Valley from the Taliban, remains nervous about Washington's intentions and the push against the new aid is reflective of that anxiety, Pakistani officials said.

Though the Zardari government is trumpeting the new aid as a triumph, officials say the language in the legislation ignores long-held prerogatives about Pakistani sovereignty, making the $1.5 billion a tough sell.

"Now everyone has a handle they can use to rip into the Zardari government," said a senior Pakistani official involved in the American-Pakistani dialogue but who declined to be named because he did not want to inflame the discussion.

The expanding American security presence has become another club. DynCorp has attracted particular scrutiny after the Pakistani news media reported that Blackwater, the contractor that has generated controversy because of its aggressive tactics in Iraq, was also in Pakistan.

Recently, there have been a series of complaints by Islamabad residents who said they had been "roughed up" by hefty, plainclothes American men bearing weapons, presumably from DynCorp, one of the senior Pakistani officials involved with the Americans said.

Pakistan's Foreign Office had sent two formal diplomatic complaints in the past few weeks to the American Embassy about such episodes, the official said.

The embassy had received complaints, and confirmed two instances, an embassy official said, but the embassy denied receiving any formal protests from the Foreign Office. It also declined to comment about the presence of Blackwater, now known as Xe Services, in Pakistan.

American officials have said that Blackwater employees worked at a remote base in Shamsi, in Baluchistan, where they loaded missiles and bombs onto drones used to strike Taliban and Qaeda militants.

The operation of the drones at Shamsi had been shifted by the Americans to Afghanistan this year, a senior Pakistani military official said.

Several Blackwater employees also worked in the North-West Frontier Province supervising the construction of a training center for Pakistan's Frontier Corps, a Pakistani official from the region said.

There was considerable unease about the American diplomatic presence in Peshawar, the capital of the North-West Frontier Province, one of the senior government officials said. Politicians were asking why the United States needed a consulate in Peshawar, which borders the tribal areas, when that office did not issue visas, he said.

Another question, he said, was why did the consulate plan to buy the biggest, and most modern building in the city, the Pearl Continental hotel - which was bombed in a terrorist attack this year - as its new headquarters.

As Parliament prepared to discuss the American aid package Wednesday, the tone of the debate was expected to be scathing. On a television talk show, Senator Tariq Aziz, a member of the opposition party, called the legislation "the charter for new colonization."

"People think this government has sold us to the Americans again for their own selfish interests," said Jahangir Tareen, a former cabinet minister and a member of Parliament, in an interview. "Some people think the United States is out to get Pakistan, to defang Pakistan, to destroy the army as it exists so it can't fight India and to break down the ISI's ability to influence events in India and Afghanistan. Everyone is saying about the Americans, ‘Told you so.' "