"The enemy is different and we must think and act anew," Kerry said in excerpts of remarks prepared for delivery in West Palm Beach, Florida. "We have to do everything we can to stop a nuclear weapon from ever reaching our shore and that mission begins far away."

In the second of three speeches on national security, Kerry is expected to propose a new high-level White House job to oversee efforts to prevent a terrorist attack using nuclear weapons and recommend speeding up a current program to secure nuclear material in the former Soviet Union.

"The greatest threat we face today (is) the possibility of al-Qaeda or other terrorists getting their hands on a nuclear weapon," Kerry said. "Osama bin Laden has called obtaining a weapon of mass destruction a 'sacred duty."'

The senator from Massachusetts, a 20-year veteran of the Foreign Relations Committee, also said he wanted to end nuclear programs in countries like Iran and North Korea.

Kerry has criticized President Bush for refusing to hold bilateral negotiations with North Korea. He has said he would adopt a two-track policy of continuing the six-party talks that include Russia, Japan, China and South Korea while also holding direct discussions with Pyongyang.

After the Sept. 11, 2001 attacks on the United States, Kerry said Americans needed to "take away politics, strip away the labels" and ask honest questions.