You know the old line: "you can't be too thin or too rich?" The foreign policy equivalent would be "you can't be too secure."  Because there is no agency or institution that can protect states from each other, realists generally view security as the highest aim of states. The need for security encourages governments to remain watchful about emerging dangers and to avoid squandering resources unnecessarily on fanciful projects or special indulgences. The need to compete effectively in the harsh world of international politics imposes a certain discipline on domestic political quarrels, and encourages competing parties to limit partisan backbiting for the good of the country.  When people say that "politics stops at the water's edge," that's what they are talking about.

Nonetheless, being too secure has a downside: It allows U.S. politicians to do and say a lot of stupid things without thinking that they might actually be putting the country at risk. Case in point: the Republican Party's absurd objections to the New Start treaty with Russia, which seem to be based solely on the desire to prevent the Obama administration from logging even a modest political success.

The New Start treaty is not a major strategic breakthrough, but that's just the point. It's a modest agreement that will save us some money in the long-term, reduce strategic uncertainty, make it easier to enlist Russian cooperation on other issues, and make the United States look a bit less hypocritical when we try to convince other states to forego nuclear weapons themselves. But none of that matters to today's Grand Obstructionist Party (GOP) leaders, in sharp contrast to isolated Republic moderates like Richard Lugar (R-IN) or veteran officials like Henry Kissinger or James Baker, all of whom support the treaty.

But the taproot of this foolishness isn't just the poisonous know-nothingism of today's Republican Party. The underlying permissive condition for this behavior is America's extraordinarily secure international position. Although we are constantly bombarded with alarmist reports about grave dangers facing the nation from outside, the United States remains remarkably secure compared with other states. The U.S. economy is still the world's largest and most diverse, despite its recent woes, and it is still more than twice as large as the number 2 and number 3 economic powers (China and Japan). We spend more on national security than the rest of the world put together, are the only state with global power projection capabilities, and have the world's most sophisticated nuclear arsenal. Many of the world's significant military powers are our allies, so our actual lead is even greater. There are no major powers near to our shores, and we are insulated from many global problems by two enormous oceanic moats.

The United States does face a modest problem from terrorist groups like Al Qaeda, but that is due in good part to our own ill-advised meddling in the Middle East and elsewhere. And assuming it never acquires a nuclear weapon (which we can prevent by working with others to enhance nuclear security around the world), Al Qaeda is not an existential threat to our prosperity or way of life. Even if all their thwarted plots had succeeded--and I'm very glad they didn't--the damage would pale in comparison to the costs of the Iraq and Afghanistan wars. Indeed, if history is any guide, international terrorism at its worst poses less threat to American life than auto accidents, nut allergies, or falling in a bathtub.

In short, although perfect security is beyond anyone's grasp, the United States is as secure as any state could ever expect to be. That's a wonderful thing for us Americans, but it has at least two negative consequences. First, because the United States doesn't have to worry very much about protecting its own shores from a serious military challenge, it is free to run around the world getting involved in various problems, even when it has lost sight of any underlying strategic rationale and has no clear idea why it is doing these things. For example, when you are really secure, very powerful, and have a lot of wealth to draw upon, you can keep extending the deadline in places like Afghanistan almost indefinitely, even when the costs of doing so far outweigh any likely benefits.

The second problem with being too secure is that it allows politicians to use foreign policy as a partisan political football, and to indulge special interests and other ideological fixations. When a state faces real dangers -- as the United States did during World War II or the Cold War -- it has to set priorities carefully and avoid squandering resources on whims. But when a state is as secure as America is today, then partisan politics will loom larger and become nastier. Without a "clear and present danger" to focus the national mind, presidents find it harder to face down pressure from groups with strong but focused agendas, whether the issue on the table is defense spending, Middle East policy, or trade. Moreover, exploiting foreign policy issues in order to bash the president doesn't seem to place the country in immediate danger, so members of the opposition can do so without being accused of compromising national security.

Don't get me wrong: I'm not arguing that the United States would be better off if we faced a really serious external threat again. On balance, I'd rather be strong, wealthy, and insulated from major dangers. But there is a real cost to our present condition: we end up doing a lot of things we shouldn't, and we don't do a lot of things we should. The end result is that our position in the world will gradually erode, and then we'll have to start taking this stuff seriously again.