President Bush says next week's summit of leading industrialized nations is a chance to show Iran that the world is serious about stopping it from developing a nuclear weapon. European diplomats expect Tehran will respond to an international offer to resolve the dispute before the start of that meeting in Russia.
President Bush says the St. Petersburg summit of the Group of Eight should reaffirm international opposition to Iran enriching uranium.
"The G-8 will be an opportunity for those of us involved with this issue to make it clear to the Iranians that we are firm in our resolve for them not to have a nuclear weapon," said Mr. Bush.
Speaking to reporters at a new conference in the Midwest city of Chicago, President Bush repeated his offer that, if Iran verifiably suspends enriching uranium, the United States will join direct talks on the issue.
Efforts to arrange those talks are being led by European officials, who say there has been constructive progress in laying the ground for Iran to respond to an international package of incentives for suspending uranium enrichment.
European Union foreign policy chief Javier Solana met with Iran's top nuclear negotiator, Ali Larijani, in Brussels Thursday. Solana's spokeswoman says the talks were a good start, and Solana expects that Iran will offer what she calls a substantive response to the offer before the start of next week's G-8 summit.
One of the obstacles for President Bush is summit host Vladimir Putin. The Russian president opposes the threat of sanctions against Iran if it does not comply with international demands.
"You know, some nations are more comfortable with sanctions than other nations," he added. "And part of the issue we face in some of these countries is that they have got economic interests. And part of our objective is to make sure that national security interests, the security of the world interests, trump economic interests. And sometimes that takes awhile to get people focused in the right direction."
President Bush telephoned President Putin this week, and said he believes the Russian leader understands the dangers of Iran having a nuclear weapon.
Iran says it is not developing a nuclear weapon, and is enriching uranium solely for the peaceful civilian purpose of generating electricity.