RIYADH, Saudi Arabia — US Defense Secretary Robert Gates told Saudi leaders Wednesday that the US effort for diplomatic engagement with Iran had come to naught and he asked for the influential kingdom's help to win wide backing for biting economic penalties against Tehran.The offer of talks with Iran to resolve doubts about the intent of its nuclear program remains on the table, US officials said, but the United States has moved away from making outreach to Iran the primary goal."We are certainly hopeful that the Saudis will use whatever influence they have, which is considerable, in this region and throughout the world to try to help us in our efforts at the U.N. so that we can get meaningful sanctions enacted against Iran," Pentagon press secretary Geoff Morrell said following Gates' sessions with Saudi King Abdullah and other senior leaders.The predominantly Sunni Arab Middle East — and Gulf nations in particular — have been wary of the growing influence of Shi'ite Iran, and Saudi Arabia has long warned of the potential for a nuclear arms race in the Gulf region if Iran gained the bomb.Saudi Arabia and other Sunni states see Iran's expanding missile capability as a more immediate threat.The US military is trying to reassure Gulf allies by buttressing its defense systems with upgraded Patriot missiles on land and more US Navy ships capable of destroying missiles in flight.The Patriot missile systems, which originally were deployed in the region to shoot down aircraft, have now been upgraded to hit missiles in flight. Iran claims its nuclear program is aimed at the peaceful production ofenergy. The United States and Western allies openly scoff at thatclaim, and worry that Iran is closing on the means to build a weapon isbehind the latest push for United Nations Security Council penalties onIran's powerful Revolutionary Guards Corps.If approved, the new sanctions would be the fourth set of penalties applied to Iran over its disputed nuclear program.The Saudi foreign minister has expressed doubts about the usefulness ofmore sanctions on Iran, saying the world needs a quicker and moredirect approach."We see the issue in the shorter term because we are closer to thethreat," Prince Saud al-Faisal said when US Secretary of State HillaryRodham Clinton visited the Saudi capital in February. "We needimmediate resolution rather than gradual resolution."Gates held no public events with Saudi officials Wednesday.