The smiles didn't take away from the tough line. US Secretary of State Condoleezza Rice's message to Pakistan's new government was blunt. "We talked at length about the importance of Pakistan taking its responsibility to deal with those who may use Pakistan territory even if they are non-state actors."

Rice also reflected on the nature of the attack, and she was clear Pakistan needs to act now.

"There is urgency to get to the bottom of these attacks, urgency to bring perpetrators to justice and urgency to use this information to disrupt and prevent further attacks."

But Pakistan is still refusing to take any concrete measures. Ater Rice's visit, came a staple Pakistan comment: "Pakistan will assist India in probing the attack , Pakistan is determined to ensure its territory will not be used for any act of terrorism and they will take strong action against any Pakistani element found involved in the Mumbai terror attacks."

Though now Zardari may find it far more difficult to get away with just talk, the US this time seems determined not to turn a blind eye.

The chairman of the US joint chief of staff Admiral Mullen, who met top Indian leaders in Delhi on Thursday - a day after he was in Pakistan -- has pledged the US military's support to combat terrorism in the region.