By Arun Kumar

Washington, April 7 (IANS) President Barack Obama has put combating nuclear proliferation and nuclear terrorism at the "top of America's nuclear agenda" to win a commitment from various nations to secure all vulnerable nuclear materials within four years.

"For the first time, preventing nuclear proliferation and nuclear terrorism is now at the top of America's nuclear agenda, which affirms the central importance of the Nuclear Non-Proliferation Treaty (NPT)," he said announcing his administration's new nuclear strategy.

"We have aligned our policies and proposed major funding increases for programmes to prevent the spread of nuclear weapons around the world," Obama said unveiling the strategy ahead of next week's nuclear security summit.

The summit, Obama said, "will be an opportunity for 47 nations to commit to specific steps to pursue the goal of securing all vulnerable nuclear materials around the world within four years."

Prime Minister Manmohan Singh is expected to be one of the key speakers to initiate the discussion on national action plans at the summit.

By the new strategy the US will also swear off the development of new generations of nuclear weapons and will not use its existing arsenal to attack non-nuclear states that are in compliance with non-proliferation agreements.

Outlined in the "Nuclear Posture Review", the new American stance is meant to provide an incentive for countries to stay within the rules of the 1968 NPT, a senior administration official said.

India has declined to sign the NPT on the ground that it's discriminatory, but diplomatic sources pointed out that New Delhi has for all practical purposes been in compliance with the treaty obligations for nuclear weapon states.

Defence Secretary Robert Gates, Secretary of State Hillary Clinton, Energy Secretary Steven Chu and Adm. Mike Mullen, the Joint Chiefs of Staff chairman, announced the change two days before Obama is to sign a new nuclear arms treaty with Russia that reduces both countries' missile stockpiles.

The new policy "recognizes that the greatest threat to US and global security is no longer a nuclear exchange between nations, but nuclear terrorism by violent extremists and nuclear proliferation to an increasing number of states," Obama said later in a statement.

"Moreover, it recognizes that our national security and that of our allies and partners can be increasingly defended by America's unsurpassed conventional military capabilities and strong missile defences."

He noted the US will not conduct nuclear testing and the administration will seek ratification of the 1996 Comprehensive Test Ban Treaty.

The position "provides a road map" to help achieve Obama's "long-term goal of a nuclear-free world," Gates added. It removes a "calculated ambiguity" in past US nuclear policy while making clear that "this is a weapon of last resort," he said.

Gates also noted, however, the new policy sends a "strong message" to states such as Iran and North Korea.

"If you're going to play by the rules [of the NPT], we will undertake certain obligations to you," he said. "But if you're not going to play by the rules ... all options are on the table."

Gates made clear that if a non-nuclear state uses chemical or biological weapons, it could still be subjected to a massive conventional response. He also warned the US "reserves the right to make any adjustment to this policy" warranted by the future development of biological weapons.