Lieberman, I-Conn., said Wednesday during a stop in Islamabad that he was told sufficient safeguards had been put in place to protect the weapons, Dawn newspaper reported.
Among the senior officials Lieberman met were Pakistan's army chief and Lt. Gen. Khalid Kidwai, chairman of the Strategic Planning Division, the report said.
Lieberman called his meeting with Kidwai very "important and successful," adding it was encouraging to learn Pakistan's nuclear weapons are in safe hands, the report said.
"There is a multilayer security about Pakistan's nuclear arsenals and I will take a good message about it for the U.S. Senate," Lieberman said.
He also said in the Dawn report that Pakistan's military leaders were clear about fighting terrorists and extremists by containing activities of al-Qaida and the Taliban in the tribal areas.