WASHINGTON, (AP) – The Obama administration says the latest round of sanctions appears to have succeeded in bringing additional pressure against Iran’s nuclear program. But private experts question whether the penalties will achieve their goal of compelling Tehran to give up any nuclear ambitions.

In a speech Monday, the Treasury Department’s point man on Iran sanctions, Stuart Levey, said U.S. and international sanctions are “dramatically isolating Iran financially and commercially.”

And he asserted that this “can and will create leverage for our diplomacy” with Iran’s leaders.

“Almost daily we receive reports of major firms around the world deciding to pull out of business dealings with Iran,” Levey said at the Center for Strategic and International Studies. The number of companies that recently have curtailed or eliminated their ties to Iran is in the dozens, he added, including Toyota and oil giant Royal Dutch Shell.

Secretary of State Hillary Rodham Clinton has said the sanctions are “biting” Iran’s economy.

Analysts generally agree sanctions are taking a toll. But will they stop Iran from getting the bomb?

Probably not, says Ray Takeyh, a Mideast expert at the Council on Foreign Relations and a former State Department adviser on Iran policy.

The policies of Iranian Supreme Leader Ayatollah Ali Khamenei and President Mahmoud Ahmadinejad “are largely unaffected by mounting financial penalties imposed by the West,” Takeyh wrote Sunday in an opinion piece in The Washington Post.

“Washington and its allies still fail to realize that they are not dealing with a conventional nation-state making subtle estimates of national interests,” Takeyh wrote. Khamenei sees reconciliation with the U.S. as subversion that could undermine the pillars of the Islamic state, he added.

In an Associated Press interview in New York on Sunday, Ahmadinejad said sanctions are futile.

“If they were to be effective, I should not be sitting here right now,” he told the AP.

Ahmadinejad also repeated Iran’s assertion that it has no intention of building a nuclear weapon.

President Barack Obama entered the White House committed to offering Tehran a chance to negotiate over its nuclear program, but by late 2009 it was clear Iran had no interest in engagement.

So the administration turned to what it calls the “pressure track,” and in June the U.N. Security Council passed a new sanctions resolution. On July 1 Obama signed unilateral U.S. sanctions legislation that he called the toughest Congress has ever imposed on Iran.

Sharing the U.S. concern about Iran potentially gaining nuclear weapons, the European Union, Australia, Canada, Japan and South Korea have imposed their own sanctions against Iran.

The sanctions have limited Iran’s ability to attract foreign investment, pinched its ability to import gasoline, created a drag on its shipping business and hurt Iranian banking relationships worldwide. But it’s not clear that these problems will translate to a shift in Iran’s nuclear stance.

Even some Obama administration officials have conceded that sanctions may fall short of their goal, which is to convince Iran’s leaders that the political costs of their continuing defiance on nuclear issues have reached an unacceptable level.

“Will it deter them from their ambitions with regard to nuclear capability? Probably not,” CIA director Leon Panetta said June 27, while adding that Iran’s true nuclear intentions are unclear.

Sami Alfaraj, an adviser to the Kuwaiti government on security and intelligence, said in an interview Monday that it’s clear the sanctions are taking a toll on Iran’s economy. Still, the pressure will fall short of compelling Iran to steer away from nuclear arms, he said.

“Sanctions alone cannot really work,” Alfaraj said.

Former Secretary of State Colin Powell has come to a similar conclusion. “I think eventually we will have to deal with the reality that sanctions may not change the views of the Iranians on these issues” of a nuclear program, Powell said Sunday on NBC’s “Meet the Press.”

Levey, the Treasury official who is implementing the U.S. sanctions campaign, said he cannot accept the idea that sanctions have no chance. But he stopped short of predicting success.

“No one knows for sure the outcome,” he said.