Mullen's agenda included meetings with U.S. military officers and with Pakistan's army chief, Gen. Ashfaq Kayani, the country's English-language newspaper Dawn reported.
Before arriving in Islamabad, Mullen said U.S. officials were concerned about terrorist safe havens and militant organizations in Pakistan, including the Haqqani network based in North Waziristan. During a news conference in New Delhi, Mullen called the Haqqani militants "the most lethal network" facing the U.S.-led international force in Afghanistan, saying he repeatedly urged Pakistan to tackle the threat.
"I continue to address that with the (Pakistani) leadership as a very, very strong priority," Mullen said.
Mullen said Kayani was aware of the U.S. concerns about Haqqani militants and "what we think needs to happen."