Obama vows to pursue further nuclear cuts with Russia

(Reuters) - President Barack Obama has vowed to pursue further strategic arms reductions with Russia as part of his broader nuclear disarmament agenda even as he issued stern warnings to North Korea and Iran in their nuclear standoffs with the West.

Speaking ahead of a global nuclear security summit in Seoul, Obama held out the prospect of new cuts in the US nuclear arsenal as he sought to rally world leaders for additional concrete steps against the threat of nuclear terrorism.

We can already say with confidence that we have more nuclear weapons than we need, Obama said in a speech at South Korea's Hankuk University, pledging a new arms-control push with incoming Russian president Vladimir Putin when they meet in May.

Obama laid out his latest plans against the backdrop of continued nuclear defiance from North Korea and Iran, challenges that have clouded his overall nuclear agenda as well as the summit getting under way in Seoul.

Obama 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 Seoul on Monday, Obama made clear that he remained committed to that notion and insisted that those who deride our vision, who say that ours is an impossible goal that will be forever out of reach, were wrong.

Though Obama was vague on exactly how such a vision would be achieved and will surely face stiff Republican opposition if he moves forward, he said he was confident the United States and Russia, which reached a landmark nuclear treaty in 2009, can continue to make progress and reduce our nuclear stockpiles.

I firmly believe that we can ensure the security of the United States and our allies, maintain a strong deterrent against any threat, and still pursue further reductions in our nuclear arsenal, he said.

But another arms accord with Moscow will be an even tougher sell to 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.

Obama also used his speech to call on North Korea, which plans a rocket launch next month, to curb its nuclear ambitions or else face further international isolation.

And know this - there will be no more rewards for provocations. Those days are over. This is the choice before you, he said, directing his comments at North Korea's leadership.

South Korean President Lee Myung-bak urged his Chinese counterpart, Hu Jintao, on Monday to try to persuade the North to cancel next month's rocket launch, which Pyongyang says is merely to send a satellite into space.

Obama told Iran time there was still space for a diplomatic solution of its nuclear issue but demanded that Tehran act urgently to show its sincerity amid talk of new negotiations with world powers.

Tehran says its nuclear program is purely peaceful, but Israel and Western nations believe it is moving towards a nuclear bomb that could change the regional balance of power.

Once again, there is the possibility of a diplomatic resolution that gives Iran access to peaceful nuclear energy while addressing the concerns of the international community, Obama said.