Medvedev said it's regrettable that Iran has not responded to many constructive proposals the international community has offered, and it's possible the United Nations Security Council will have to take up the issue.
Obama said the U.S. will not tolerate any actions by Iran that risk an arms race in the Middle East or threaten the credibility of the international community. He said he hoped to secure tough new sanctions on Iran this Spring.
Medvedev and Obama spoke after signing a new nuclear arms agreement between the U.S. and Russia in Prague. Obama added that talks to reach the treaty also yielded closer cooperation toward achieving sanctions.
Obama also said the treaty he and Medvedev signed set an example for Iran and other nations by showing that the world's two leading nuclear powers would abide by international obligations.