The Pakistani government fought back against army criticism of a proposed multibillion dollar U.S. aid package Thursday, arguing that the military had no reservations about taking such assistance when it ruled the country two years ago.

The debate came at a time when the U.S. hoped to unite all sides as the military prepared for an expected offensive against the Taliban and Al Qaeda along the nation's northwest border with Afghanistan, an operation likely to be prolonged and bloody.

But the country's pro-U.S. government has been suddenly swamped with a wave of opposition to the package, which would provide $1.5 billion a year over the next five years to Pakistan, tripling nonmilitary assistance to the country. It also authorizes "such sums as may be necessary" for counterterrorism assistance — but only if it cracks down on militancy and other conditions.

In a statement Wednesday, the army brass raised "serious concern" over strings attached to the bill, bolstering opposition politicians who have said the conditions would lead to U.S. meddling in Pakistan's affairs.

Underpinning the debate was the ongoing tensions between the fragile civilian government and the country's powerful military, which ruled Pakistan for about half of its 62-year history.

Farhatullah Babar, President Ali Asif Zardari's chief spokesman, said previous U.S. aid packages negotiated under Gen. Pervez Musharraf, who ran a military government here for eight years beginning in 1991, contained similar clauses and the army never complained.

"Why this protest now?" he asked.

He also said the army should not have gone public with its concerns.

"There are proper forums like the defense committee of the Cabinet and the Ministry of Defense for communication of such views and participating in the decision making process," he said. "Why this was bypassed, I don't know."

He strongly defended the aid package, saying "there is nothing against the national interest in the bill."

Among other strings, the bill conditions U.S. aid on whether Pakistan's government maintains effective control over the military, including its budgets, the chain of command and top promotions. The U.S. bill also includes yearly certifications that Pakistan is making a sustained commitment to combating terrorist groups and cooperating in stopping the proliferation of nuclear weapons.