If you want to know how President Obama is changing America's foreign-policy strategy, watch the short video in which he wishes Iran's people and leaders a happy Nowruz.

Nowruz is the Persian new year, an ancient holiday celebrated on the first day of spring. The president's greeting (www.whitehouse.gov/nowruz), broadcast last Friday, shows he intends to reach out to Iran.

Obama's Nowruz message was striking for what it included — and what it omitted. His words were sharply different in tone from messages sent by President George W. Bush, who considered Iran's regime part of the "axis of evil." Unlike Bush, Obama addressed Iran's leaders as well as the Iranian people, making it clear that he is not seeking regime change.

The president said clearly that "the United States wants the Islamic Republic of Iran to take its rightful place in the community of nations." But he added that such a place "cannot be reached through terror or arms."

At the same time, by sending his message on a traditional holiday not linked to religion, Obama showed his respect for the Persian nation. He praised Iran's "great civilization." And, to counter those who say past differences between our two countries can't be overcome, he quoted the words of the Persian medieval poet Saadi: "The children of Adam are limbs to each other, having been created of one essence."

Iran expert Karim Sadjadpour, of the Carnegie Endowment for International Peace, was visiting Dubai when Obama delivered his message. He said the large Iranian community there had an "overwhelmingly positive" reaction to Obama's recognition of Iran's new year and its rich culture.

Perhaps most important, Obama never mentioned Iran's President Mahmoud Ahmadinejad.

That's because Obama's message was directed at Iran's leaders — plural. He made clear that he recognizes that Ahmadinejad is not the key figure in Iran's power structure; the supreme clerical leader, Ayatollah Ali Khamenei, holds that position.

Many experts argue that Khamenei considers anti-Americanism to be an immutable tenet of the regime's ideology. Obama's new-year message, and his new policy, will put that thesis to the test.

Sadjadpour contends that the Nowruz video will provoke an internal Iranian political debate over whether Iran should take up Obama's offer of honest engagement "grounded in mutual respect." With Iranian elections coming up in June, the new U.S. approach will put the burden on hard-liners to justify continued enmity toward America at a time when Iran's economy is in deep trouble.

He thinks Obama's offer will likely increase public pressure for Iran's leaders to come down on the 2009 end of that debate.

Of course, there's no guarantee Khamenei will be responsive. It won't be easy to improve the United States' toxic relationship with Iran's Islamic republic or agree on a formula to deal with Tehran's suspect nuclear program. It's not clear whether Iran will even be willing to cooperate on areas of mutual security interest, such as stability in Iraq and Afghanistan.

And spoilers within Iran's government will try to impede warmer relations by continuing to arrest Iranian-Americans. The latest victim is 31-year-old Roxana Saberi, a freelance journalist from North Dakota who was working in Tehran before being thrown in Evin prison nearly two months ago. Her father says she is depressed and suicidal.

Yet Obama is right to throw down a challenge to Iranian leaders and test the possibility of better relations. If they choose not to respond, the onus will be on them.

Reach Trudy Rubin at (Unknown address).

Trudy Rubin is a columnist and editorial-board member for the Philadelphia Inquirer. Reach her at trubin@phillynews.com.