WASHINGTON — Iran could have enough highly enriched uranium to make a single nuclear device within a year, but it would take three to five years before the Islamic republic could manufacture a usable nuclear weapon, senior military officials told Congress on Wednesday.
The timeline, which is consistent with past U.S. government estimates of Iran's nuclear progress, suggests that there still may be a window for diplomatic and economic pressure to dissuade Tehran from becoming a nuclear power.
Marine Gen. James Cartwright, the vice chairman of the Joint Chiefs of Staff, told the Senate Armed Services Committee that Iran, which is operating thousands of centrifuges in a plant at Natanz, could have enough highly enriched uranium to fuel a weapon within a year.
However, Cartwright said, "It would take another two to three, potentially out to five years, to move from the idea of having the material to a deliverable weapon that is usable."
Other officials, who spoke only on the condition of anonymity because the intelligence is classified, said his comments reflect the findings of a soon-to-be-updated National Intelligence Estimate on Iran's nuclear program, the first in nearly three years.
The last NIE, in November 2007, said that Iran had halted its nuclear weapons program four years earlier, although it was keeping open the option to develop such weapons.
Officials in Israel and several European countries challenged that key finding, and the officials said the new estimate reflects new evidence from the International Atomic Energy Agency and other sources that indicates Iran is secretly continuing its quest for nuclear weapons despite claims that its nuclear work is solely for peaceful purposes.
"There is an NIE currently under way, and the decision on when it will be released and when it will be finished has not been determined yet," Army Lt. Gen. Ronald Burgess, the director of the Defense Intelligence Agency, told the Senate hearing.
Both Republican and Democratic senators expressed impatience with President Barack Obama's efforts to enact tougher United Nations sanctions against Iran — efforts that have been slowed by objections from China and Russia.
"It's long past the time to put teeth in our policy," said Sen. John McCain, R-Ariz. "We keep pointing the gun. We haven't pulled a single trigger yet, and it's about time that we did."
McCain, who previously has expressed support for military strikes on Iran, didn't specify what steps he had in mind.
After months of refusal, China last week agreed to join the United States and four other nations in negotiating a new U.N. Security Council resolution imposing sanctions on Iran.
However, Undersecretary of State William Burns acknowledged, under questioning from McCain, that it's "going to be very difficult" to get China and Russia to agree to a ban on Iranian imports of refined petroleum products. Such a ban could seriously damage Iran's economy because, while it has vast crude oil reserves, it lacks refining capacity.
The sanctions, instead, are expected to target the powerful Islamic Revolutionary Guard Corps and businesses it operates, along with Iranian banks and weapons imports.
The Senate has passed a bill that would sanction foreign firms that supply refined gasoline to Iran. The Obama administration has been unenthusiastic about the legislation, however, fearing it could backfire and prompt U.S. allies to lessen their support for united action against Iran.
Iran, meanwhile, has continued its defiance of U.N. demands that it halt uranium enrichment.
The country's nuclear chief, Ali Akbar Salehi, announced that it had produced five kilograms of uranium enriched to 20 percent purity, news reports from Tehran said. It takes uranium enriched to 90 percent purity to make a nuclear weapon.
The 2007 NIE said that Iran probably would be able to acquire enough highly enriched uranium for a nuclear weapon "sometime during the 2010-2015 timeframe."
Doing so would require a major retooling of its Natanz enrichment plant, or an as yet unknown covert facility. "We do not have insight that the regime has made the decision to move in that direction," Burgess told the committee.
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