By Roger Hardy
BBC Middle East analyst
What to do about Iran? The question has haunted US policy-makers since George W Bush entered the White House in 2000.
President Ahmadinejad has been gaining influence in the region
Now, frustrated by Iran's muscle-flexing in the Middle East and aware of the drawbacks of military action, the administration seems to have settled on a policy of containment.
"It is a dangerous regime," says Peter Rodman, a strong advocate of containment who was until recently a senior Pentagon official, "and we have to stand up to it."
A veteran of the Reagan administration and a protege of former Secretary of State Henry Kissinger, Mr Rodman uses the word "containment" with explicit echoes of America's Cold War confrontation with the Soviet Union.
He sees Iran as an essentially ideological threat, and puts little faith in diplomacy as a solution.
Current US policy is one of limited engagement with Iran - in an effort to find common ground on Iraq - and the application of pressures, including United Nations sanctions.
Mr Rodman regards the UN sanctions, designed to make it harder for Iran to pursue its nuclear programme, as feeble.
He wants individual countries to put pressure on banks to stop lending to Iran, and on companies to restrict investment in the all-important oil and gas sector.
Many in Washington think Iran's economy is its Achilles heel.
It is suffering from high inflation and unemployment, and there is a widespread perception that President Mahmoud Ahmadinejad has mismanaged the economy.
In June, angry Iranian motorists set fire to petrol stations to protest at the introduction of petrol rationing.
'Pressure not enough'
But Michael Hirsh, a senior editor at Newsweek, who has just returned from a visit to Tehran, thinks the administration's hopes are misplaced.
Iran has been Mr Bush's worry since day one in the White House
He does not believe economic pressure will "force the Iranians to throw up their hands and say, 'OK, we give up our nuclear programme'".
Thomas Pickering, a veteran US diplomat with long experience of the Middle East, thinks pressures alone are not enough.
"Pressures without openings - to try to resolve the impact and effect of the pressures - are just pressures," he says.
The effect, he adds, is that of a pressure cooker without a relief valve.
In dealing with Iran, the administration is handicapped by its difficulties in Iraq, where the Iranians have great influence.
It is not possible, says former State Department official James Dobbins, to stabilise Iraq and at the same time destabilise Iran.
There are some in Washington who think that, if diplomacy fails, the administration should resort to military action.
But the dangers of doing so are widely acknowledged.
Striking at Iran would further inflame the Middle East, cause Iranians to rally round an unpopular regime - and probably set back its nuclear programme by only a few years.
"Iran can't be fixed right now," says Jon Alterman, who runs the Middle East programme at the Washington-based Center for Strategic and International Studies.
The problem has to be managed, he says, even if that means passing it to the next administration - and perhaps the one after that.