WASHINGTON: Iran is the biggest threat to the United States in the Middle East, surpassing al Qaeda, which is down but not out, a senior US military official said on Friday.

“The biggest threat to the United States and to our interests and to our friends, I might add, has come into focus and it's Iran,” said the official, who spoke on condition of anonymity.

Speaking at a forum in Washington, the official said he did not believe Iran wanted to provoke a conflict, however, and added he did not know if the Islamic state had decided to build a nuclear weapon.

Next week, the International Atomic Energy Agency, the United Nations nuclear watchdog, is expected to release a report that includes evidence of Iranian nuclear research which makes little sense if not weapons related, Western diplomats said.