RIYADH, Saudi Arabia -- U.S. Defense Secretary Robert M. Gates was keeping up the pressure on Iran on Wednesday, consulting with the United States' closest and most influential ally in the Persian Gulf about how to respond to Iran's disputed nuclear program.
U.S. officials said Mr. Gates would discuss shared concerns over Iran's nuclear intentions and ballistic missile program during meetings with Saudi King Abdullah and senior leaders.
Mr. Gates arrived in the Saudi capital after three days in Afghanistan. He nearly crossed paths with Iranian President Mahmoud Ahmadinejad, who was in Kabul on Wednesday for meetings with many of the same leaders Mr. Gates had just seen.
Mr. Gates accused Iran of "playing a double game" in Afghanistan and of working to undermine the security U.S. forces are trying to help build.
Afghanistan is just one of the places where the United States has a proxy fight with Iran, and the confrontation appears to be getting nastier. The Obama administration has all but written off hopes for a diplomatic opening with Iran after three decades of enmity.
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Last week, the top American commander in the Middle East, Gen. David Petraeus, said Iran had gone from being a "theocracy to a thugocracy" in its crackdown on a reform movement following last year's elections.
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 long has warned of the potential for a nuclear arms race in the Gulf region if Iran gains the bomb. Saudi Arabia and other Sunni states see Iran's expanding missile capability as an even more immediate threat.
The U.S. military is trying to reassure Gulf allies by buttressing its defense systems with upgraded Patriot missiles on land and more U.S. Navy ships capable of destroying missiles in flight.
The Patriot missile systems, which originally were deployed in the region to shoot down aircraft, now have been upgraded to hit missiles in flight.
