Syria, Iraq, and Yemen are burning up. An ascendant Iran is reconfiguring the geopolitics of the Middle East. With every passing day, Turkey is inching away from the Western orbit as Vladimir Putin's Russia has emerged as a key power-broker in the region. The Sunni monarchies' grip on their discontented populaces is looking tenuous as oil continues its slide. All of this is happening, and what are we talking about? Israel's presence in the West Bank, of course!

For this, blame Barack Obama's long-running feud with Benjamin Netanyahu, who had the bad humor of not seeing eye to eye with the president of the United States. Breaking with longstanding tradition, the U.S. recently allowed a U.N. resolution condemning Israeli "settlements" in the West Bank to pass, and followed it up with a petulant, Israel-bashing speech by Secretary of State John Kerry. Now, the issue refuses to die. On the right, Ted Cruz has introduced legislation to defund the U.N. until the resolution is rescinded; on the left, lobbying groups such as J Street are running a full-court press for the outgoing administration.

The key issue is Israeli "settlements" in the West Bank, a catch-all term that includes both settler outposts and, to some, the city of Jerusalem itself. To many Israel critics, "settlements" and the Israeli "occupation" of the West Bank are not only an obstacle to peace, but are illegal under international law; on the pro-Israel side, the argument about the legality of those settlements is typically sidestepped completely. Supporters point out that, as long as Palestine remains hostile toward Israel, it's ridiculous to say the settlements are the main obstacle to peace.

But I want to make a separate argument here, which is that the endlessly asserted point that "settlements" and "occupation" are "illegal" relies on a very tendentious reading of the law and the facts — one which should, in the final analysis, be rejected.

If there is any place where the tired cliché that "the past isn't over; it isn't even past" applies, it is certainly the Middle East. When people talk about Israel's history, the year that is endlessly cited is 1967, when, during the Six-Day War, Israel gained sovereignty over the territories still in question.

The story goes like this: The Six-Day War was illegal; during that war, Israel gained territories; therefore Israel's occupation of those territories is illegal.

What makes a war "legal" or "illegal" is murky and tendentious at best. When we talk about "the law," we typically mean not just a body of legal texts, but a state that has a monopoly on the legitimate use of force that can apply the law. When it comes to relationships between states, there is no such entity. While the U.N. is a useful body, it has nowhere near the legitimacy to say what wars are "legal" or not "legal."

I'm not saying that there is no such thing as international law. But when it comes to the laws of war, there are longstanding principles of international law which much predate the U.N.; the U.N. tries to reflect those standards but only does so fitfully and imperfectly. In looking at what wars are legal and legitimate, we must not look just at what U.N. resolutions say, but at what longstanding principles of international law say. The technical term is jus ad bellum, Latin for "the right to war." These criteria have been theorized for millennia, and U.N. resolutions only imperfectly reflect them.

Bearing that in mind, what really matters about the Six-Day War and the territories Israel accrued as a result is that Israel waged the Six-Day War in defense against violent provocation from pro-Palestinian groups. This often gets obscured because, militarily, Israel struck first. But the conflict was provoked by Egypt, which breached the conditions for the cease-fire that had prevailed between Israel and Egypt since the Suez Crisis. The cease-fire was maintained by a United Nations force staying in the Sinai, which Egypt's dictator expelled, before closing the Straits of Tiran to Israeli shipping, thus closing the Red Sea and the Suez Canal to Israeli shipping. Israel had always maintained (and reiterated right before) that closing the Straits of Tiran was a declaration of war. Israel fired the first shot, but Egypt, which had previously allied itself with Jordan and Syria and other Arab states, might as well have declared the war.

I'm not saying the Israelis were the "good guys" and the Arabs were the "bad guys." The point is that, under longstanding principles of jus ad bellum, the Six-Day War was legal. Israel was provoked by an action to which war is a legitimate response.

What about the territories won by Israel? Even if the war itself was legitimate, isn't territorial expansion by conquest illegitimate, and isn't Israel's sovereignty over those lands an illegal occupation?

Consider this: Almost every single piece of territory held in sovereignty by any single state was gained through military conquest. A thousand years ago, "France" was little more than Paris and the surrounding area. Today, France is the single largest country by land area in Europe, and every single piece of territory there was either gained or maintained through military conquest, often several times. All of the United States was built by conquest. Nobody claims that California, or Alsace-Lorraine, are illegitimate, even though they were won through military conquest.

The point is not that all territorial gains through conquest are legal or legitimate. The point is that there must exist some standard by which territory gained through conquest is legitimate, or else every state is an occupier, and every piece of territory is an illegal occupation, which is absurd. Given the circumstances of the Six-Day War, the idea that Israel's gain of those territories is illegal or illegitimate is ridiculous.

Or at least, that's what I believe. It's a frustrating aspect of this debate that we keep getting bogged down in minute details of events that happened decades ago when really they are proxies for who you support or don't support. People on both sides will find ways to say that the other side is awful and illegitimate. But this is not a warrant for relativism. It is a warrant for discernment.