Navy SEALs destroyed part of the helicopter before leaving bin Laden's compound May 2 to keep the latest U.S. military technology secret, but the tail was left behind.
Kerry, D-Mass., chairman of the Senate Foreign Relations Committee, said its return was the first of "a specific series of steps that will be implemented in order to get the [U.S.-Pakistan] relationship on track," The Washington Post reported.
"There are members of Congress who aren't confident that it can be patched back together again," he warned the Pakistanis. "That is why actions, not words, are going to be critical to earning their votes."
Kerry, who co-authored a $7.5 billion aid package bill for Pakistan, is visiting as the bin Laden raid and other events have put U.S.-Pakistani ties in crisis.
He said the raid was kept secret from Pakistan for "operational security," not out of distrust.
Pakistan's Dawn newspaper said it would be a tough diplomatic mission for Kerry, who will try to help determine for U.S. President Barack Obama whether Islamabad can continue to be an ally.
The report said in his meetings with top Pakistani civilian and military leaders, Kerry would pose some frank questions about bilateral relations. Before leaving the United States he had been quoted as saying he would press Pakistani leadership to demonstrate "real commitment to fight terrorism."
His comments in Afghanistan were equally hard-edged.
"Yes, there are insurgents coming across the border, yes they are operating out of North Waziristan [in Pakistan] and other areas of the sanctuaries, and yes, there is some evidence of Pakistan government knowledge of some of these activities in ways that is very disturbing," he said.
The Dawn report quoted analysts as saying Kerry is the best choice for Obama to convey a firm message to Islamabad because the senator is known as a friend of Pakistan in Washington but is also not reluctant to deliver tough messages.