What is the news mainly about?

The United Nations Nuclear Agency says Iran has started enriching uranium at an underground facility. The International Atomic Energy Agency also says Iran has set up more than 1,000 centrifuges for enrichment at the plant. The IAEA made the claim in a confidential document. The enrichment process can be used to create fuel for nuclear reactors or in the creation of nuclear weapons. U.S. Defense Secretary Robert Gates says diplomatic efforts to isolate Iran for its nuclear program are working. Gates says two UN Security Council resolutions imposing sanctions on Tehran for its refusal to stop enriching uranium should be given a chance to work.