There's been a lot of talk lately about whether the United States should be speaking directly to Iran.

The issue heated up after Iranian President Mahmoud Ahmadinejad sent a highly unusual 18-page letter to President Bush last week. It was the first direct communication from an Iranian leader to the White House since U.S.-Iranian relations were severed more than a quarter century ago.

The letter was highly critical of America and didn't mention the nuclear issue. The Iranian leader declared "liberalism and Western-style democracy" a failure and said President Bush should "return to the teachings of the divine prophets."

Yet the mere fact of the letter — whatever its real intent — is fascinating. So is the Iranian president's follow-up remark that Iran was "ready to engage in dialogue with anybody."

Perhaps Ahmadinejad aimed to deflect attention from the Security Council debate over whether to use diplomacy or sanctions to ensure that Iran's nuclear program doesn't produce weapons. But his dramatic move raises the question of why, after so many years, Americans and Iranians still aren't talking face to face.

There's a long, tortured history of failed efforts at U.S.-Iranian dialogue. Efforts by Presidents Carter and Clinton went nowhere. President Reagan's Iran-Contra venture ended badly.

Talks on Afghanistan between U.S. and Iranian officials helped U.S. efforts there, though Iranian officials complain they got little credit. Some former U.S. officials say that in spring 2003, Iranian officials indicated interest in a "grand bargain" with the United States. That effort fell flat, and we still don't know whether it had the support of Iran's Ayatollah Khamenei.

With the election of the conservative Ahmadinejad, any prospects for dialogue seemed dim. The Iranian leader called for Israel to be wiped off the map and questioned the reality of the Holocaust.

U.S. and European leaders say Iran's nuclear program is aimed at making a bomb. They want Tehran to stop its uranium enrichment program, while Iran insists the program is peaceful. Tehran insists it has the right to enrich, while Washington won't rule out a military option to end Iran's nuclear program. But most experts think bombing Iranian sites would not stop the program and would enmesh the United States in another long-term conflict.

Yet the White House has left negotiations with Tehran to the Europeans and the Russians. Washington OK'd talks (which have yet to start) between the U.S. ambassador in Iraq, Zalmay Khalilzad, and Iranian officials, but specified that Iraq would be the only subject on the table. With the stakes so high and the gap so wide, why aren't the two sides talking directly about a range of issues?

Talking is no panacea, but there are strong arguments for face-to-face meetings. Serious diplomacy requires active, and direct, U.S. participation. Moreover, the United States can't expect the support of other nations for stronger measures if it hasn't expended every effort to make diplomacy work.

Then there is the issue of Iraq. The overthrow of Saddam Hussein and the rise to power of Iraq's Shiites has greatly strengthened the power of Iran in the region. Iraq can't be stabilized unless all of its neighbors — including Iran — cooperate with one another and the United States. That, in turn, requires serious U.S.-Iranian dialogue.

Finally, with so much mistrust between Iranians and Americans, why wouldn't the United States want an embassy in Tehran, which would facilitate more exchanges of academics, students and businesspeople? With so little accurate information about Iran reaching here, why wouldn't the White House want more direct contacts?

I put this question to John Bolton, the U.S. ambassador to the United Nations and a hawk on Iran. "What would be the downside of direct negotiations with Iran?" I asked. He snapped back, "Legitimizing the regime, among other things."

Here we come to the nub. The administration apparently believes that broad dialogue with Iran would confer U.S. approval of its Islamist political structure.

Yet Ronald Reagan had no problem in talking directly to Soviet leaders. Reagan critiqued the Soviets on human rights even as he negotiated on nuclear weapons. He used the term "evil empire," yet didn't hesitate to bargain with the Kremlin.

Some on the Bush team may still nourish the illusion that Iran's regime is about to fall. There is no evidence to suggest this. So why leave the field to Iran's Ahmadinejad to startle the world?

Why not take the initiative and propose a dialogue with Iran aimed at addressing a broad range of issues? This would require accepting the reality of Iran's regime, but not endorsing its behavior.

Such a move would offer at least a chance of finding a diplomatic exit from the standoff over Iran's nuclear program. If Reagan talked to leaders of a system he disliked, why not Bush?

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