The North Atlantic Treaty Organization's secretary general has called on China to increase transparency regarding its nuclear weapons capabilities, and engage in the creation of an international framework on arms control.

Jens Stoltenberg spoke via video link at a NATO conference in Washington on Tuesday, touching on security challenges NATO member counties are facing.

He said that China is rapidly growing its nuclear arsenal without any transparency about its capabilities, and it is estimated the country will have 1,500 warheads by 2035.

He said as a global power, China has global responsibilities, and that Beijing would also benefit from the increased transparency, predictability and security of arms control agreements.

At the conference, US Deputy Secretary of State Wendy Sherman criticized Russia for its announcement in March that it was preparing to station tactical nuclear weapons in neighboring Belarus.

She called it a managed escalation of Russian President Vladimir Putin's war in Ukraine, and said that the United States will remain watchful of the development.