US Secretary of State Hillary Rodham Clinton has told an international conference that Iran has left the world little choice but to take harsher action to contain its nuclear program.
Clinton told the US-Islamic World Forum in Doha, Qatar that Iran has not lived up to its nuclear obligations.
She also said Iran has rebuffed US and international efforts to engage in serious negotiations on the nuclear issue.
As a result, Clinton said in her speech Sunday, the US and others are working on "new measures" to try to persuade Iran to change its course.
The United States and some of its allies suspect Tehran is using its civilian nuclear program as a cover to build nuclear weapons. Tehran denies the charge and says it only has peaceful intentions.