Despite the emergence of terrorism as the most visible national security threat, nuclear proliferation isn't yet a threat of the past, though the presidential candidates are dealing with it in very different ways.

"It is not the wild fantasy of thriller novels, but a very real possibility that terrorists could acquire a nuclear weapon or materials and use it against the U.S. and its interests. It is appropriately on the agendas of [George] Bush and [John] Kerry," said Jon Wolfstahl, deputy director of the nonproliferation program at the Carnegie Endowment for International Peace (search).

The Democratic senator has lambasted the White House, saying its efforts to control nuclear proliferation have slowed since the Sept. 11, 2001, terror attacks. Kerry charges that the president has been "fixated" on Iraq while ignoring other threats.

"Part of the approach of the administration is they don’t view [securing nuclear weapons] as the very high priority. Important, but not a priority," Wolfstahl said. On the other hand, "Kerry is surrounded by people who think this is the nation's highest priority."

The Bush campaign has hit back at Kerry, not only pointing to success in Libya and progress on North Korea, but also saying the best way to combat nuclear terrorism is to kill terrorists, not track down weapons.

"As long as you have terrorists, the number one goal, quite frankly, is the elimination of terror," Georgia Sen. Saxby Chambliss said in a conference call arranged by the Bush campaign early this month. "President Bush has taken the right approach of eliminating bad guys. When you do that, you automatically remove their ability to use those weapons."

Chambliss said Bush's strategy has reaped rewards in Libya, which has recently agreed to give up its nuclear aspirations.

The candidates' tactics for securing nuclear weapons are broadly similar, but Kerry wants a more ambitious timeline and said he would be ready to devote more political capital to the project.

On a campaign swing in Florida, the Massachusetts senator said he would appoint a national coordinator for nuclear terrorism and counterproliferation, and make nuclear proliferation a top item on the agenda with Russia.

Much of the challenge of dealing with nuclear proliferation runs through Moscow, say analysts. Russia has one of the world's biggest nuclear arsenals, but the country's leaders have not made it easy to negotiate on limiting nuclear proliferation.

"The obstacle is not the lack of an official in the White House with a special title. The obstacle is the Russians' willingness to cooperate," said former White House deputy homeland security adviser Richard Falkenrath, who said Kerry's strategy is unlikely to work with the Russians.

Center for Defense Information (search) research analyst Victoria Samson said that Russian nuclear weapons are under "somewhat shaky military control," and it should be a priority to secure them. She called nuclear proliferation one of the biggest threats facing America, and acknowledged that working with the Russians is difficult but "has proved to be feasible. It can be done; it just takes some careful thinking."

Samson said she's worried that with the "Bush administration's focus on terrorism as the end all and be all for any government action, what they're doing is really cheapening what happened with Sept. 11" and glossing over nuclear proliferation issues.

Wolfstahl said that because the White House was not making nuclear proliferation a top priority, talks with Russia have not made progress. "Making progress with Russia is hard work. It takes concerted effort, and the Bush administration has not put in the hard work."

But securing Russia's arsenal is not the key to protecting America from nuclear terrorism, said Jack Spencer, senior policy analyst at the Heritage Foundation (search).

"I think that killing a third of Al Qaeda leaders, removing Afghanistan as a base for terrorists to operate" as well as continuing operations in Asia and elsewhere "does a whole lot more to stem proliferation than throwing more money at the Russians," he said. "As long as there's a demand, there's going to be a supply somewhere. Executing the war on terrorism is a very important element of stemming proliferation."