The State Department said Hakimullah was responsible for a failed May 2010 attempt to detonate a car bomb in New York’s Times Square besides several key incidents.
The spokesman said the State Department of US could not confirm the death of Mehsud.
Dialogues with Pakistan on bilateral relations were continue, the spokesman further said.
AFP Adds: The United States Monday admitted to “tensions” and occasional “misunderstandings” in its relations with Pakistan, but implicitly defended the killing of TTP chief Hakimullah Mehsud.
The government in Islamabad reacted angrily to the attack on Hakimullah Mehsud, saying it would scuttle its peace talks with the group.
“There inevitably will be some tensions and occasional misunderstandings between our two countries,” White House spokesman Jay Carney said.
“We hope to continue to make progress in the relationship, and we continue to seek ways for our countries to cooperate on the entire range of shared interests that we have, from economic to security issues.”
Carney would not confirm the drone strike that killed Mehsud, in line with normal practice in such attacks, but he said the Tehreek-e-Taliban Pakistan (TTP) leader had a long list of extremist credentials, including a failed bombing in Times Square, New York, in 2010.
Carney charged that Mehsud and other TTP leaders had “publicly vowed to continue targeting the United States and Americans.”
Mehsud was also wanted in connection with the killings of seven Americans at a US base in Khost province, Afghanistan.