President Barack Obama's administration recently suspended about a third of its $2.7 billion annual defence aid to Pakistan in the wake of the raid that killed Osama bin Laden in Abbottabad.

We are in a very difficult time right now in our military-to-military relations," Joint Chiefs of Staff Chairman Admiral Mike Mullen told a press briefing billed as his last before retirement.

And the retiring admiral said he hoped the two nations would soon find a way to "recalibrate" those ties.

Still, Mullen acknowledged: "we need to work through the details of how this (recalibration) is going to happen."

On a visit to Washington, Pakistan's former military ruler Pervez Musharraf staunchly defended the army and ISI. He denied any Pakistani support for bin Laden, who apparently moved to the garrison town of Abbottabad while Musharraf was in power.

Copyright AFP (Agence France-Presse), 2011