China must have a limited nuclear “second strike” force to deter foes from threatening it with atomic weapons, the nation’s main military newspaper said on Thursday, in a rare account of Beijing’s nuclear strategy.

The commentary in the official Liberation Army Daily comes during intensifying atomic diplomacy — after a nuclear security summit hosted by U.S. President Barack Obama and before an international conference in May about the future of the nuclear Non-Proliferation Treaty (NPT).

China has been gradually modernising its relatively small nuclear arsenal and some critics of proposals to cut dramatically Western nuclear forces have said uncertainty about Beijing’s plans should deter such proposals.

Retired People’s Liberation Army Major General Xu Guangyu said in the newspaper commentary that China wanted a minimal nuclear deterrent and would avoid any arms race.

“China resolutely adheres to a defensive nuclear strategy, and has always adhered to a policy that it will never be the first to use nuclear weapons at any time and under any circumstances,” wrote Xu, now a researcher in the state-run China Arms Control and Disarmament Association.

“The most basic feature of China’s nuclear strategy, in a nutshell, is to be a deterrent but present no threat.”

The commentary does not suggest China is rethinking its nuclear doctrine, but spells out in uncommonly sharp terms Beijing’s rationale for upgrading its atomic forces.

AUTHOR ADDRESSING DOUBT ON CHINESE STANCE

In a telephone interview, Xu told Reuters the commentary was intended to address worries about China’s nuclear stance, especially in Japan, India and the United States.

The United States and Russia this month signed a pact to cut their much larger atomic arsenals, and Obama separately announced a shift in U.S. doctrine, vowing not to use atomic weapons against non-nuclear states that abide by the NPT.

Like all the nuclear weapons states, China is secretive about its arsenal, developed from a first atomic test explosion in 1964. The Stockholm International Peace Research Institute has estimated that by 2009 China possessed 186 deployed strategic nuclear warheads.

Under the new treaty, the United States and Russia will limit their deployed nuclear warheads to 1,550 each, 30 percent fewer than the limit set in a 2002 treaty.

Members of the U.S. Senate could make an issue of China when debating whether to ratify the new pact with Russia. Some U.S. opponents of deeper nuclear arms cuts have said sharp reductions could allow China to “sprint to parity”.

China must have a nuclear force that is “real, reliable, effective, and keeps up with the times”, Xu wrote.

That force includes a “second-strike” capability so China can retaliate if it comes under nuclear attack, he added.

This force, he wrote, “is able, should a foe launch an initial nuclear strike, to really possess, and to convince the other side that it faces, an intolerable second-strike nuclear capability, thereby deterring an enemy from using nuclear weapons against us.

“It must make them grasp, without the least ambiguity, that we possess a deterrent.”

China’s efforts to upgrade its nuclear forces include gradually replacing older, liquid-fuelled ballistic nuclear-capable missiles with solid-fuel missiles, which will make launching them faster and less cumbersome.

China is also building new “Jin-class” submarines, capable of launching nuclear warheads while at sea.

“International experience shows the most effective second-strike capability is submarines,” Xu told Reuters. “That and the upgraded missiles are a focus.”

(Editing by Benjamin Kang Lim and Ron Popeski)