Secretary of State Condoleezza Rice said Thursday the Bush administration's decision to break with past policy and send a top diplomat to weekend talks with an Iranian envoy proves the international community is united in trying to eliminate threats from the Iranian nuclear program.

"The point that we're making is the United States is firmly behind this diplomacy, firmly behind and unified with our allies and hopefully the Iranians will take that message," Rice said.

"It's going to be very clear to them that the international community and P5-plus-1 are completely united," she told reporters at the State Department.

The P5-plus-1 is the group of the five permanent members of the U.N. Security Council and Germany that has offered Iran incentives to halt activities that could lead the development of nuclear weapons.

Senior diplomats from the group will meet on Saturday in Switzerland with Iran's chief nuclear negotiator to hear Tehran's final response to the incentives package. For the first time, the United States will participate in such a meeting with the Iranians with the State Department's third-ranking diplomat, William Burns, scheduled to attend.

Previously, the administration had refused to deal directly with the Iranians until they suspended their uranium enrichment and reprocessing activities. U.S. officials say Burns will be listening, not negotiating, and that his presence is a sign of America's commitment to peacefully resolve the dispute over Iran's nuclear program.