VIENNA, Austria – Iran threatened the United States with “harm and pain” Wednesday if the U.S. tries to use the U.N. Security Council to punish Tehran for its suspect nuclear program.

Washington warned that Tehran has enough nuclear material for up to 10 atomic bombs.

The rhetoric reflected the intensity of the debate at a meeting of the International Atomic Energy’s 35-nation board over a critical report on Iran’s nuclear program. The meeting ended late Wednesday, formally opening the path to Security Council action that could range from a mild statement urging compliance to sanctions or even military measures.

The meeting also set the stage for a potential struggle between Washington, which seeks harsh measures against Tehran, and Moscow, which advocates a softer line.

But the head of the IAEA cast approaching Security Council involvement as a continuation of diplomacy with Iran.

Mohamed ElBaradei also suggested that Washington might need to talk to Tehran directly if negotiations reach the stage of focusing on security guarantees to Tehran in exchange for concessions on its nuclear program.

“Once we start to discuss security issues my personal view [is] that at one point the U.S. should also be engaged into a dialogue,” ElBaradei told reporters.

Tehran and Washington broke diplomatic relations shortly after Iranian radicals seized the U.S. Embassy and took diplomats there hostage in 1979. Although the United States has swung support behind negotiations with Iran conducted in recent months by Russia and by France, Britain and Germany, it has refused direct contacts.

Iran claims its nuclear program is peaceful and only aimed at generating electricity, but an increasing number of countries have come to share the U.S. view that Tehran is seeking to develop atomic weapons.

The next step after Vienna is for ElBaradei’s report to be sent to the United Nations in New York for council review and action.