(Lazaro Gamio/The Washington Post)

Foreign policy debates are usually confined to the ivory tower corners of Washington think tanks and government agencies. But the arguments over the Iran nuclear agreement burst out of that realm long ago.

Since the deal was reached in July, every passing week has brought a new, open letter to Congress signed by one set of people or another weighing in on its merits or shortcomings.

Frequently one letter spawns a follow-up letter, from people expressing the opposite viewpoint.

After 36 retired generals and admirals signed a letter in support of the deal, 195 retired generals and admirals wrote a counter letter urging Congress to reject the deal.

A letter of support last month carried the signatures of 340 American rabbis, not to be confused with a similar supportive letter from 350 rabbis in Israel. Then came a letter from more than 1,000 rabbis who want Congress to vote no on the deal.

Letters pro and con began rolling in shortly after the deal was announced on July 14, and have picked up speed as Congress nears a mid-September vote on whether to disapprove the deal. On Wednesday, the White House secured enough support to sustain a veto.

Many advocates on both sides are keeping track of how many people have signed each letter, as if it were another sports statistic.

“Once it began, I understand why it became an arms race,” said Omri Ceren, managing director of the Israel Project, a nonpartisan organization. “It’s interesting, politically and sociologically.”

The Iran agreement finalized in Vienna after a lengthy negotiation between Iran and six world powers, including the United States, is a complicated document, filled with highly technical and interdependent details involving nuclear science. In essence, the agreement eases a host of international sanctions if Iran pares back its nuclear program and allows inspections to guarantee it isn’t building a nuclear weapon.

It is hugely controversial, in part because it involves a government with a history of enmity to U.S. interests and in part because the Israeli government considers it an existential threat.

Letters pro and con began rolling in shortly after the deal was announced on July 14, and has picked up speed as Congress nears a mid-September vote on whether to disapprove it. Hundreds of letters have been penned, not by the typical special interest groups, but by ad hoc groupings of people of similar professions or circumstances that add weight to their opinions.

Nuclear scientists, arms control experts and foreign affairs scholars have all checked in with their own missives to Congress, as have former U.S. ambassadors, former ambassadors to Israel, former Israeli intelligence officials and Iranian dissidents.

Then there are groups of people who don’t usually engage in big foreign policy issues.

An open letter was signed by 78 current and former student government presidents from around the country who asked Congress to “say no to bad Iran deal.”

When an open letter endorsing the agreement was signed 98 prominent members of the Jewish community in Los Angeles, including many with Hollywood links like Mad Men creator Matthew Weiner, producer Norman Lear and architect Frank Gehry, it was the last straw for Michael Doran, a Middle East security expert at the Hudson Institute who was in the National Security Council under President George W. Bush. Doran took to Twitter with his reaction.

Doran said he believes the White House has coordinated the pro-deal letters. During a recent visit to Israel, he said, he heard one of the signatories to what’s known as the Hollywood letter interviewed on the radio saying the White House had asked him to do it.

“President Obama wants to blunt the accusation he’s hostile to Israel by mobilizing members of the liberal Jewish community,” said Doran, an opponent of the deal. “I doubt whether Frank Gehry is really up on the national security concerns of Israel. And Norman Lear! What is Norman Lear’s view on the inspections regime? That’s what I want to know.”

It’s not clear whether the barrage of letters will ultimately have much of an impact, said Ryan Enos, a social scientist who studies political behavior at Harvard.

“If they wanted to write to a member of Congress, they’d write a closed letter,” he said. “What they’re trying to do is signal the public and Congress at the same time.”

Rabbi Yonah Bookstein of Pico Shul in Los Angeles said the almost 1,100 rabbis who signed the letter he helped organize against the deal represent every denomination in Judaism, a point of pride.

“We’re approaching three to one opposed to the deal,” he said, comparing the anti-deal letter to its pro-deal counterpart. “I don’t want to put down anybody else’s letter. Everybody deserves their voice. But this one distinguishes itself by the breadth of support it has.”

Some people have been reluctant to take a public position.

Anthony Zinni, the retired Marine Corps general who headed Central Command, said he was asked to sign both letters circulated by retired flag officers, and declined to sign either one. He said that’s in part because he considers it too early to judge a deal that relies on the as-yet unproven sincerity of all the parties involved.

“I think they’re taking a political position rather than making a sincere judgment on the quality of the agreement,” he said. “And I don’t know if it’s Neville Chamberlain or an agreement that will stand. I think most people who sign up don’t have a depth of understanding to really know.”

So what are Americans to make of the plethora of contradictory letters? Zinni says, not much.

“Do I like the idea of trying to resolve things through dialogue? Yes, because the alternative is not good,” he said. “But the agreement is just a starting point, the judgement comes in a year or two. My answer always is, call me in a few years and ask me if it’s a good agreement or not.”