More countries have access to the ingredients necessary for making nuclear bombs than at any time in the world's history.  Experts testifying at a U.S. Congressional hearing on Homeland Security say tougher controls and greater cooperation between countries are needed to reduce the threat to the international community.

Stockpiles of fissile material, the key ingredient in nuclear weapons, are growing at an alarming rate and according to leading experts so is the threat of the materials falling into the wrong hands.

Physicist David Albright, with the Institute for Science and International Security, says that since 2003, estimates of more than 3700 metric tons of plutonium and highly enriched uranium have been accounted for in about 60 countries. 

He says that's enough fissile material to make hundreds of thousands of nuclear weapons. 

"You don't need that much to make a bomb, and again it adds to the urgency of the problem, that this cannot be set aside and it does require the U.S. government to take the lead because we care the most and we recognize the danger the most," the physicist told the U.S. representatives.

Russia currently has the largest stockpiles of plutonium and highly enriched Uranium, followed by the United States.  But Mr. Albright says the growth of military stocks in India, Pakistan and Israel are cause for concern because of the potential for terrorists getting a hold of the materials.

Despite U.S. intentions to reduce its own stockpiles by 50 percent by the year 2012, Rose Gottmoeller with the Carnegie Endowment for International Peace says progress on a non-proliferation treaty has been slow.

"Part of the reason for that is the very strong division between those who believe the U.S. and other nuclear weapons states are not fulfilling their obligations," said Ms. Gottmoeller.

Iran is currently building a uranium enrichment facility that could be used to produce fissile material for nuclear weapons. But Mr. Albright says countries like North Korea or Iran will require other nuclear capable nations to set more than just a good example.

"I think we can solve the problem of Iran but it's going to have to do with dealing with Iran's own perceptions of its security and being able to offer incentives so that it feels that if it gives up something, it gets something in return."

Experts say better intelligence, security, and universal compliance are needed to reduce the global threat. Dr. Albright says, high on the list will be international and verifiable agreements on downblending -- a term used for converting stockpiles of weapons-grade uranium to lower-grade materials that can be used for peaceful purposes.