Letter to Iran marks a dangerous watershed for U.S.

Foolish as it was -- and it was extremely foolish -- the letter sent to Iranian authorities this week by 47 Republican senators was more dangerous than it was foolhardy. Those who authored it no doubt think of themselves as patriots; they no doubt believe deeply in the concept of American exceptionalism, and they clearly advocate a strong American presence on the global stage.

But in their stubborn righteousness, in their self-satisfied belief that they and only they are the wise and proper spokesmen for this country, they have made the United States look weak in the eyes of the world. They have taken the true source of whatever influence we might carry -- our unity -- and they have debased it. They have done real harm to this country.

There's no excuse for it.

Not so long ago, we still understood that if you want to win a debate, you win it here, on these shores. If you have problems or disagreements with your nation's leadership, you deal with it amongst your fellow citizens, through the processes available to you.

You don't invite foreign leaders into your councils of government to undercut your own duly chosen leaders, no matter how much you may dislike those leaders. Nor do you reach out to a foreign enemy, opening your own negotiation channels, to try to sabotage the policies of those who were elected by your people and designated in the Constitution to handle those responsibilities.

When we speak to the world, we speak in one voice, as the United States of America, not as subsets of Americans who can be played off each other for the advantage of outsiders. We do not allow outsiders to divide us. We don't invite outsiders to become players in our own affairs.

The standard maxim invoked in such discussions is of course that "politics stops at the water's edge," a phrasing that goes back to 1947. But the sentiment that it expresses runs much, much deeper. It can also be found in the Logan Act, which since 1799 has forbid private citizens from conducting their own individual versions of American foreign policy counter to that of the government.

It states:

"Any citizen of the United States, wherever he may be, who, without authority of the United States, directly or indirectly commences or carries on any correspondence or intercourse with any foreign government or any officer or agent thereof, with intent to influence the measures or conduct of any foreign government or of any officer or agent thereof, in relation to any disputes or controversies with the United States, or to defeat the measures of the United States, shall be fined under this title or imprisoned not more than three years, or both."

The Republican letter to Iranian leadership clearly violates both the spirit and the letter of the Logan Act, leading some to suggest that prosecution might be warranted. By the letter of the law, they're correct, but as a practical matter the suggestion is almost as foolish as the letter itself. If we can't enforce such understandings through our joint identity as Americans, if we are really and truly forced to rely on the threat of prosecution to remind elected officials of the gravity of their actions -- if that's how far we've sunk, then the battle is already lost.

And it's not just an American ideal, or a post-WWII ideal. It gets down to the basic understanding of a nation state and how it functions. You can go back thousands of years, to the days of the Greek city states and beyond, and even there you will find it well understood that in matters of diplomacy and war, a successful nation speaks with one voice and only one voice. It is and has always been a fundamental of international relations, of human relations.

Think of it on the smallest scale possible. Think of it in terms of a married couple trying to negotiate the purchase of a house or car, but bickering between themselves at the settlement table, with one partner trying to undercut the other. That's how we've now presented ourselves to the rest of the world.

And at the national level, the problem is that once such understandings are violated, once such taboos are broken, they become much more difficult to reinstate. With this example now set, it becomes much easier for malcontents of either party to follow it in the future.

And other nations, having watched this play out, will now begin to factor it into their own calculations. If they are told "no" by an American adminstration, they now have hope of being told "yes" by another branch of that government. If they are told "yes" by an administration, they now have cause to doubt whether that "yes" can really be counted upon.

The question of an Iranian nuclear weapons program is one of a handful of the most pressing foreign-policy challenges that we face. But the issue of who sets and carries out American foreign policy, the issue of whether we are even capable of acting as one actor on the world stage, with one voice and one mind, is much more fundamental and important.

And that makes this week's events deeply, deeply troubling.