The US' decision to suspend military aid to nuclear-armed Pakistan was not taken lightly as the Trump administration was concerned that the country's atomic weapons could fall into the hands of terrorists, National Security Adviser John Bolton has said.
Mr Bolton said the war against terrorism is a matter of extraordinary importance to America.
In his address to a Washington think-tank on Monday- the Federalist Society for Law and Public Policy Studies - Mr Bolton also said that the US wanted Pakistan to cooperate fully in the war against terrorism.
"It was before my time, but the Trump administration did not take the decision to cancel a substantial part of the military aid package to Pakistan lightly," he said.
"It was done knowing full well that Pakistan is a nuclear weapons state, and the risk that the government could fall into the hands of terrorists that would get control of those nuclear weapons was particularly serious."
In January, US President Donald Trump suspended most of America's military aid to Pakistan, saying Islamabad allowed the Taliban to use its territory for attacks in Afghanistan.
Last week, the Pentagon asked Congress to allow it to use for other purpose, the funds that had been set aside for Pakistan. The re-allocation ended the possibility that the funds earmarked for Pakistan could be released if Islamabad agreed to take the required action against various terrorist groups.
During his visit to Islamabad last week, US Secretary of State Mike Pompeo had pressed the new Pakistani government to rein in the groups operating from its soil.
Mr Bolton said Secretary Pompeo wanted to convey the message that "we hoped and expected that Pakistan would cooperate fully in the war against terrorism, which they had committed to do."