The US Defense Secretary and Chairman of the Joint Chiefs of Staff, by their recent remarks, seem to be playing 
The option of military action [is] off the table.
into Iranian hands and giving them a go-ahead for their nuclear program. They have done so by taking the option of military action off the table. Any close listener or reader of the recent remarks of Secretary of Defense Robert Gates or Admiral Michael Mullen understands this.
On March 11, 2009 Secretary Gates told National Public Radio that the United States has to be especially careful in regard to any possible intervention in Iran. He said this would be done only if the continental United States were threatened. Iran presently has missiles capable of covering the Middle East and, in the latest development, capable of reaching southern Europe. Its further efforts are evidenced by the recent launching of a satellite working to extend such capabilities. Once the Iranians register Secretary Gates remarks, they will understand well enough that it is alright for them to proceed with nuclear enrichment and weaponization so long as they do not test an intercontinental missile capable of reaching the United States.
Admiral Mullen told the Charlie Rose Show on March 12, 2009 that the United States is concentrated above all on the Afghanistan-Pakistan situation. With its additional involvement in Iraq, he explained, America is not eager for military preemption now - even should that come not from the United States directly, but from its ally Israel.
Both Israel and the United States believe that Iran is determined to achieve a nuclear weapons capability. Israeli Intelligence Chief Amos Yadlin believes Iran already has the technical capability. Non-proliferation expert David Albright of ISIS believes the Iranians already have enough low-grade enriched uranium to produce a bomb. Admiral Mullen puts the earliest time for an Iranian nuclear weapon as 2010; given the fact that we already are into 2009, that is not so much time. There is a clear sense everywhere that Iran is on the verge of acquiring nuclear weapons, if not there already.
The US political and military echelons are clearly opposed to Iran attaining nuclear weapons. They understand the strategic changes this will entail in the Middle East, including a possible nuclear arms race. They know it may lead to the breakdown of non-proliferation agreements in other areas. They know, too, that it increases the likelihood of nuclear war.
Nonetheless, Mullen concurs with Gates in believing that the US simply cannot afford another intervention now. They are afraid of the consequences of any preemptive strike, both militarily and politically. They are also arguing 
Mullen concurs with Gates in believing that the US simply cannot afford another intervention now.
that any Israeli strike might have disastrous consequences for American interests in the Gulf and in Iraq. They seem at times to be actually lobbying against an Israeli preemptive effort, saying it would endanger US interests.
It is by this time well known that President George Bush rejected, in early 2008, Prime Minister Ehud Olmert's requests for the ordnance and fly-over space required for an Israeli preemptive effort. It does not at all seem likely that President Barack Obama will prove more hawkish and trustworthy on this issue than President Bush. Instead, the United States is moving in the direction of talking with Iran, presenting them a package of incentives to prevent their persistence in the pursuit of nuclear military capability. Given every bit of evidence to this point - which includes years of Iranian defiance of the IAEA, lying and stalling - there can be little realistic expectation that the Iranians will give up on what they consider a major strategic goal.
So, the United States, in effect, has adopted a policy which Vic Rosenthal of the pro-Israel website FresnoZionism.com calls, "All carrots and no sticks". It is a policy which will buy the US a little short-term peace at the expense of serious, and possibly disastrous, long-term harm to its allies and interests.