WASHINGTON AND BEIRUT — Iran unveiled what it described as a new air defense system during an annual military display Sunday while policymakers in Washington confronted new reminders about their limited range of options for responding to Tehran's apparent buildup.
The new system, which Iran said is designed to defend against attacks by missiles and high-altitude planes, was introduced as the government awaits sophisticated missile defense batteries it bought from Russia but which have been delayed because of pressure on Moscow from Israel.
Tehran's assertion of new military advances came amid disclosures that Defense Secretary Robert Gates wrote to White House officials in January to warn more options were needed to prevent Iran from acquiring nuclear weapons. U.S. officials and their allies charge Iran wants to develop such weapons, while Iran says its research program is aimed at developing civilian nuclear energy.
The memo from Gates to White House National Security Adviser James Jones, first reported by the New York Times, decried the lack of a long-term strategy for addressing Iran's plans. A U.S. government official confirmed the existence of the memo Sunday.
U.S. officials and analysts have long agreed they have poor options, given Iran has been defiant in the face of economic sanctions and that a military strike would be difficult, costly and is only likely to delay any nuclear program by a few years.
However, it is highly unusual for a senior Cabinet member to stress concerns over administration options, as Gates did in his memo.
Administration officials challenged an assertion in the New York Times that the memo prompted a re-evaluation of the administration's approach to Iran.
"It is absolutely false that any memo touched off a reassessment of our options," said Ben Rhodes, a spokesman for the National Security Council. "This administration has been planning for all contingencies regarding Iran for many months."
But the memo came during a period when Gates and other top officials were pushing to develop a broader range of responses to the process Iran is following in its nuclear research.
In December, Adm. Michael Mullen, chairman of the Joint Chiefs of Staff, asked the Pentagon's Joint Staff to develop additional options, including possible military alternatives, in an effort to instill a sense of urgency in the planning process, officials said Sunday.
Those options have not been described and remain a tightly held secret.
Gates has estimated that Iran is about a year away from having enough enriched uranium for an atomic weapon. However, the Iranians would likely need another two to five years or so to develop a weapon, U.S. officials believe.
"It depends on where they are, and we do not have perfect visibility because of the closed nature of that society into where they really are," said a military official.