Obama vows to pursue nuclear cuts with Russia

US President Barack Obama vowed on Monday to pursue further nuclear arms cuts with Russia, saying the United States has more warheads than necessary, and issued stern warnings to the Democratic People's Republic of Korea and Iran in their nuclear standoffs with the West.

Speaking ahead of the Nuclear Security Summit in Seoul, Obama held out the prospect of new reductions in the US arsenal as he sought to rally world leaders for additional concrete steps against the threat of nuclear terrorism.

He pledged a new arms-control push with incoming Russian president Vladimir Putin when they meet in May. But any further reductions would face stiff election-year opposition from Republicans in Congress who already accuse him of weakening America's nuclear deterrent.

Obama laid out his latest strategy against the backdrop of continued nuclear defiance from the DPRK and Iran, twin challenges that have clouded his overall nuclear agenda and the summit in Seoul.

He set expectations high in a 2009 speech in Prague when he declared it was time to seek "a world without nuclear weapons". He acknowledged at the time it was a long-term goal, but his high-flown oratory helped him win the Nobel Peace Prize.

In his speech, Obama said that even after new Strategic Arms Reduction Treaty, signed between the United States and Russia in 2010, the United States will still have more than 1,500 deployed nuclear weapons, and some 5,000 warheads.

Obama said the United States will continue to seek discussions with Russia on reducing not only strategic nuclear warheads, but also tactical weapons and warheads in reserve.

Regarding nuclear security, Obama said that the international community has made it harder than ever for terrorists to acquire nuclear materials, but much is still being stored without adequate protection.

For the upcoming Nuclear Security Summit, Obama expected that more tangible and concrete commitments to secure or completely remove nuclear materials will be made by participants.

As for the peaceful use of nuclear power, Obama said, "with rising oil prices and a warming climate, nuclear energy will only become more important. Yet the process of producing nuclear energy also makes it possible for terrorists to reach nuclear weapons. Therefore, improving nuclear security is crucial for the safe use of nuclear energy."

Obama voiced confidence the United States and Russia, which reached a landmark arms-control treaty in2010, "can continue to make progress and reduce our nuclear stockpiles".

But another arms accord with Moscow will be a tough sell to US conservatives who say Obama has not moved fast enough to modernize the US strategic arsenal, a pledge he made in return for Republican votes that helped ratify the START treaty.