Pakistan on Tuesday reacted to a report on U.S. concerns about its nuclear arsenal by saying it has extensive protection measures and a robust control system for its atomic weapons that are aimed at maintaining stability in South Asia.

The remarks by Pakistan’s Foreign Office came in response to a report in The Washington Post that said the U.S. spends billions monitoring adversaries like Al Qaeda and Iran but has an “equally intense focus” on its “purported ally” Pakistan and has ramped up surveillance of its nuclear arms.

“Pakistan is fully committed to the objectives of disarmament and non-proliferation. As a nuclear weapons state, Pakistan’s policy is characterised by restraint and responsibility”, Foreign Office spokesman Aizaz Chaudhry said.

He further said Pakistan’s “nuclear deterrence capability is aimed at maintaining regional stability in South Asia”. Islamabad has established “extensive physical protection measures, robust command and control institutions under the chairmanship of the Prime Minister, comprehensive and effective export control regulatory regimes to ensure safety and security of nuclear installations and materials”, he said.

“We follow best international practices and standards set by the International Atomic Energy Agency”, Mr. Chaudhry said in a statement.

Pakistan is also fully engaged with the world community on nuclear safety and security issues. The efficacy of its strategic export controls have been acknowledged by experts from international export control regimes during interactions on various occasions, he said.

“The country is a party to both the Chemical Weapons Convention and Biological Weapons Convention and is fully implementing the two regimes”, Mr. Chaudhry said.

Citing a 178-page summary of the American intelligence community’s “black budget”, The Washington Post reported the U.S. had ramped up its surveillance of Pakistan’s nuclear arms and was concerned about its biological and chemical arms sites.

The daily said the classified document was provided to it by former National Security Agency contractor Edward Snowden, who leaked some of America’s most closely guarded secrets.

Pakistan is believed to have about 120 nuclear warheads.