* Existing sanctions could be enforced more vigorously
* Iran unlikely to soon move full speed on atomic weapons (Refiling to add dropped words in quote in third paragraph that do not materially change meaning)
WASHINGTON, March 9 (Reuters) - The United States believes Iran intends to get to the brink of a nuclear arms capability so it could make them if it wished, a senior U.S. official said on Wednesday.
However, Robert Einhorn, the U.S. State Department’s senior adviser for nonproliferation and arms control, said, he does not believe Iran soon plans to attempt a nuclear “breakout” -- abandoning its commitments under the Nuclear Non-Proliferation Treaty and moving full-speed to toward atomic weapons.
“We believe that at a minimum Iran is moving to the threshold of a nuclear weapons capability,” Einhorn, said in response to a question at a Washington think tank, making clear that he was talking about Iran’s intentions rather than its current capabilities.
The United States believes Iran is seeking to acquire nuclear weapons under the cover of a civil nuclear program. Iran denies this, saying it program is solely to produce electricity so it can export more of its oil and gas.
Speaking to the Arms Control Association think tank, the official said major powers decided after meeting Iranian officials in Istanbul this year that they needed to resume pressuring Tehran to abandon its suspected nuclear ambitions.
He said the United States is not now seeking fresh U.N. security sanctions but said that existing sanctions could be carried out more rigorously and that fresh bilateral steps or those taken by like-minded countries were also possible.
He offered no details on possible new sanctions other than to say that a number of alternatives were being studied.
The official said the main determinant of whether Iran may pursue a nuclear “breakout” was a political decision to do so.
Given the current relative inefficiency of its uranium enrichment technology -- a process that can produce fissile material for power plants or, if refined much further, for bombs -- he said it would make little sense for Iran to make such a choice now.
“That’s provided some confidence that they are not going to break out soon because it would make no sense for them to break out with a machine that produce material so inefficiently,” he said. “We don’t see breakout as imminent at this stage.” (Reporting by Arshad Mohammed; Editing by Jackie Frank)