Democrat Barack Obama warned Wednesday about the danger of "fighting the last war" as he pledged to focus on emerging nuclear, biological and cyber threats if elected president.

Among those joining him for a panel discuss at Purdue University were two potential running mates, Sen. Evan Bayh, D-Ind., and former Sen. Sam Nunn, D-Ga. As the former governor of a Republican state, Bayh could help Obama. Nunn, a defense expert from the South, would burnish the ticket's experience.

When asked if he were interested in the job or had provided material to Obama's campaign, Bayh referred reporters to the campaign. Nunn said he thought an Obama-Nunn ticket was unlikely.

"If anyone offered me any high office in U.S. government, I'd be greatly honored and I'd talk to him. Certainly I would talk to Sen. Obama if he wanted to talk about it, but I think the chance of an offer are pretty slim," Nunn said.

Obama said two goals of his administration would be to secure all loose nuclear material during his first term, as well as rid the world of nuclear weapons.

He said adhering to nonproliferation treaties would put pressure on nations such as North Korea and Iran. North Korea has tested a nuclear weapon and Iran has an energy program the Bush administration warns could be a precursor to nuclear weapons development.

"As long as nuclear weapons exist, we'll retain a strong deterrent. But we will make the goal of eliminating all nuclear weapons a central element in our nuclear policy," Obama said.

He added, "The danger ... is that we are constantly fighting the last war, responding to the threats that have come to fruition, instead of staying one step ahead of the threats of the 21st century."

Despite the policy focus, politics permeated the event.

Bayh repeatedly extolled the virtues of Obama, despite having supported Hillary Rodham Clinton in the Democratic primary campaign.

Recalling a trip he and Obama made to Iraq, Bayh said in his introduction of Obama: "He was pragmatic, he was focused, although he was wise enough to oppose that conflict from the beginning because he understood it was a strategic diversion. He's now tough enough to get us out and to do it in the right way, refocus on Afghanistan and Iran and the other real threats that are evolving."

Nunn, 69, is viewed as a senior statesman who could offset the relative youth of Obama, a 46-year-old freshman senator from Illinois. He said he supported Obama's nonproliferation pledge and outlined the challenges Obama would face in the Oval Office as if he were already elected.

Afterward, when asked about his interest in the vice presidency, Nunn said: "I've never aspired to that office. It's always nice to have your name mentioned. It's an honor, but I have no expectations of being offered any office, and I am not in any way sitting on the edge of the chair waiting to go back into government."

During his opening, Obama also paid tribute to Sen. Richard Lugar, a popular Indiana Republican who has focused on nuclear nonproliferation issues for much of his career, working closely with Nunn. Continued...