Feelings may boil over if the war drags on
US Secretary of State Colin Powell is the most senior member of the Bush administration to visit Pakistan, now considered a frontline state in the US-led campaign against terror.
Pakistan's role in the operations against Osama Bin Laden and his Taleban hosts is crucial for both tactical and strategic reasons.
Having nursed and supported the Taleban since its advent in the early 1990s, Pakistan's knowledge of the organisation, its leaders, its strength and weaknesses is unsurpassed.
Washington needs this intelligence for a successful operation.
Logistical help
Pakistani airspace is important for air and missile attacks from warships and submarines operating in the Arabian Sea off Pakistani shores.
The use of the Pakistani bases at Jacobabad in Sindh and Pasni on the Baluchistan coast will be critical to any future land operations in south-eastern Afghanistan, the Taleban's heartland.
Mr Powell will be keen to reinforce the bonds of military co-operation that have characterised US-Pakistani relations for decades.
The fact that both he and President Pervez Musharraf share a military background should help establishing rapport.
But having agreed to abandon its former Afghan proteges, Pakistan too needs US support.
Support needed
Protests against Islamabad's aid to the anti-Taleban coalition have rocked several Pakistani cities in the past week.
Led by vocal minorities, these have remained manageable.
But if operations continue and civilian casualties mount, agitation could spread and stretch to breaking point the ability of the state to remain in control.
General Musharraf's recent military reshuffles should strengthen moderate forces at command levels.
However, the troops - many of them Pashtuns with tribal or clan links across the border - could become restive.
Since the army is General Musharraf's only effective support base, keeping the military united is his first priority.
Endgame fears
President Musharraf's military backing would be endangered if the US-supported Northern Alliance succeeds in its bid to replace the Taleban in Kabul.
The Northern Alliance is made up overwhelmingly of Uzbeks, Tajiks, and Hazaras, while the Taleban are ethnic Pashtuns.
Pakistan's worry is that a non-Pashtun regime in Kabul could ignite Pashtun nationalism in Pakistan itself.
The fact that India - as well as Russia, Iran, Uzbekistan and Tajikistan - have been providing support to the Northern Alliance deepens Pakistan's fears of having to face enemies across both its eastern and western borders at the same time.
It will prove very difficult for Mr Powell to reassure his Pakistani allies and still maintain the objectives of the coalition.