Israeli Prime Minister Benjamin Netanyahu is in a difficult situation. He faces the undeniable threat of a nuclear-capable Iran and, as a political and military fact, needs the United States as an ally in preventing that rogue nation from acquiring nuclear weapons.

The trouble is, he wants that U.S. support on his own terms, going so far this week as to instruct the American voters that the country must have a "red line" that, once crossed by Iran, will provoke a military attack.

There are two significant problems with that.

One is that, as columnist Fareed Zakaria pointed out in the Washington Post last week, no country would limit its options that way, or signal to an adversary when an attack would be imminent. Indeed, Israel itself has not drawn that kind of red line regarding Iran's nuclear ambitions. Instead, it seeks to raise the pressure on Iran and to push the world toward confrontation.

The other problem is that Netanyahu, despite his protests to the contrary, inserted himself directly and unwisely into American politics. That violated a fundamental rule of international diplomacy, and in doing so created the risk of undermining his own cause.

Elections are an internal matter, even if their outcomes influence the course of events in other nations. It is enough to put up with the misleading advertising that each side throws at voters without also having to tolerate foreign leaders sticking their oars into our water. That can cause resentment and drive away the very support those leaders are hoping to attract.

A nuclear-armed Iran would be an international disaster, first and foremost for Israel but also for the entire Middle East and the rest of the world. The United States understands that. The U.S. ambassador to the United Nations, Susan E. Rice, said after Netanyahu's comments that there is "no daylight" between the United States and Israel and that President Obama "will do what it takes" to prevent Iran from acquiring a nuclear weapon, including military action if necessary. But, she said, "we are not at that stage yet."

After nearly 11 years of war, voters in this country might be skeptical of a candidate who draws such red lines cavalierly.

Israel is facing a difficult time, but the answers are not easy. It may be hurting more than helping its cause when its leader treads on American politics.