WEST LAFAYETTE, Indiana (CNN) -- Sen. Barack Obama on Wednesday said he wants to rid the world of nuclear weapons and pledged to fight emerging threats posed by biological and cyber-terrorism.
Sen. Barack Obama joins in a roundtable discussion on national security Wednesday at Purdue University.
"It's time to send a clear message to the world: America seeks a world with no nuclear weapons," the White House hopeful said.
"As long as nuclear weapons exist, we'll retain a strong deterrent. But we'll make the goal of eliminating all nuclear weapons a central element in our nuclear policy."
The remarks, delivered at Purdue University in Indiana before a roundtable discussion with foreign policy experts, come as the senator from Illinois is preparing for a trip abroad. Obama also is seeking to gain traction on national security issues.
In a fact sheet distributed to reporters, Obama's campaign said he will work to eliminate all nuclear weapons, but will not commit the United States to giving them up while other states retain them.
Going after one of John McCain's signature issues, the war in Iraq, the presumptive Democratic presidential nominee said invading the country after the September 11, 2001, attacks has allowed other emerging threats to develop. Watch what Obama says about the fight against terrorism »
"Instead of taking aggressive steps to secure the world's most dangerous technology, we have spent almost a trillion dollars to occupy a country in the heart of the Middle East that no longer had any weapons of mass destruction," he said.
"It's time to update our national security strategy to stay one step ahead of the terrorists -- to see clearly the emerging threats of our young century and to take action to make the American people more safe and secure.
"It's time to look ahead -- at the dangers of today and tomorrow rather than those of yesterday. America cannot afford another president who doesn't understand the threats that confront us now and in the future," he said.
Obama, who plans to visit Europe and the Middle East this month, said nuclear terrorism is "the gravest danger we face," and said he would seek to rally international support to place increased pressure on Iran and North Korea over their apparent nuclear ambitions.
"Both of these nations have a history of support for terror," he said. "Both should face strong and increasing sanctions if they refuse to verifiably abandon their illicit nuclear programs. And both demand sustained, aggressive and direct diplomatic attention from the United States, and that's what I'll provide as president."
The presidential candidate also pledged to protect the country from the threat of biological and cyber attacks.
"We know that the successful deployment of a biological weapon -- whether it is sprayed into our cities or spread through our food supply -- could kill tens of thousands of Americans and deal a crushing blow to our economy," he said.
The campaign also said Obama will seek to secure all nuclear weapons materials in four years and to increase funding by $1 billion a year to make sure nuclear weapons are removed from vulnerable sites around the world.
The scene of Obama's remarks was no accident -- Indiana is a state that has long voted Republican in presidential elections but one the Democrat's campaign is hoping to make competitive this cycle. Taking part in the roundtable discussion with Obama was Indiana's Democratic U.S. senator, Evan Bayh, a popular figure from a powerful political family.
Obama also went out of his way to praise Indiana's other senator, Republican Dick Lugar. The two teamed up in the Senate on legislation seeking to curb the threat of loose nuclear weapons.
Former Sen. Sam Nunn of Georgia also joined Obama in the discussion. Nunn is considered one of the most respected Democratic voices on national security issues and, along with Bayh, is said to be on Obama's short list for vice president.
Shortly after Obama concluded his remarks, the McCain campaign released a letter signed by 10 retired admirals and generals touting the senator from Arizona's national security credentials.
"This country has learned the peril of treating terrorists and their state sponsors as little more than a law enforcement problem," the letter said. "We are unanimous in our view that the failures of the past should not be repeated, and we believe that John McCain's long record of national service, and his demonstrated judgment on matters of national security, make clear who can best defend this country abroad, and assure peace and prosperity at home."
The retired military officials who signed the letter were Navy Adm. Ronald J. Hays, Navy Adm. James L. Holloway, Navy Adm. Jerome L. Johnson, Marine Corps. Gen. P.X. Kelley, Army Gen. James J. Lindsay, Air Force Gen. John Michael Loh, Navy Adm. Leighton W. Smith, Army Gen. Carl Stiner, Coast Guard Vice Adm. Donald C. "Deese" Thompson and Coast Guard Vice Adm. Howard B. Thorsen.