Washington (CNN) -- In what appears to be an attempt to call Iran's bluff on its nuclear program, the United States is poised to offer Tehran a way to obtain medical isotopes that Iran says it desperately needs to treat cancer patients, according to the State Department.
The United States, along with "other countries," will present a new proposal to the International Atomic Energy Agency to provide Iran with those isotopes, State Department spokesman P.J. Crowley said Tuesday.
"Our point is, if Iran feels it has a specific need, we are willing to engage constructively and try to identify ways in which the international community and potentially the United States can meet that need," Crowley said.
The move appeared to be a response to Iran's announcement Monday that it will carry out its own uranium enrichment to 20 percent to provide fuel to make the isotopes. The United States, along with other countries, questioned Iran's motives for that enrichment, saying it increases Iran's ability to produce fuel for a nuclear weapon.
Crowley told reporters that under the new proposal, the international community would "facilitate Iran's procurement of medical isotopes from third countries."
"There are alternatives," Crowley said. "The Iranian decision to improve their processing to 20 percent is an unnecessary step." Providing the opportunity to buy the isotopes directly, Crowley said, would be the "fastest and cheapest" way for Iran to avoid running out of isotopes and could help "build confidence."
Tehran separately has rejected an IAEA proposal under which it would ship most of its low-enriched uranium out of the country for further enrichment by Russia. France would process that uranium into fuel rods that would then be returned to Iran.
The new offer from the United States comes as Washington and other major countries move closer to imposing harsh new sanctions on Iran over its nuclear program, which those countries say is designed to develop a nuclear weapon. Iran says its nuclear program is exclusively for peaceful purposes.
President Obama told reporters on Tuesday that the international community will try to pressure Iran more if Iran is not willing to cooperate.
"What we are going to be working on over the next several weeks is developing a significant regime of sanctions that will indicate to them how isolated they are from the international community as a whole," Obama said.
Presenting details of the latest proposal, the State Department spokesman said, "We stand ready to work with Iran, we stand ready to address its legitimate needs, but we need to see Iran come to the table prepared to address our concerns and the concerns of the international community regarding its nuclear ambitions."