The last time I was on the Israeli-Syrian border looking at the ruined Syrian city of Quneitra was thirty years ago. I was fifteen and taking a summer course in Israel. And an Israeli soldier manning a border position was explaining to my class the mechanics of this tense but oddly stable border, over which Israelis and Syrian forces stared at each other but which---unlike the Lebanese border---remained stable over long periods of time. I was struck, I recall, by the visible presence of a United Nations outpost, and I asked the soldier what the UN's role along this line was. He responded in a heavy Israeli accent with amused contempt---and no small amount of truth: "Well, eh, they monitor, eh, the situation very carefully so that if anything happens, eh, they can get out before they get hurt." It is a comment that has conditioned my view of many UN operations ever since.

I returned today to that same spot overlooking Quneitra to find the Syrian army gone. The UN is still there, and still monitoring the situation very carefully. There's a cafe at which some of them hang out on the Israeli side called "Coffee Anan"---which is a double pun in Hebrew because "Anan" means cloud and the cafe is at the top of a high peak. But on the other side of border, there are no Syrian troops any more. Quneitra fell a few months ago to the Al-Nusra Front. And the Syrian army has not come back. Where I once looked across the line at Syria, the crossing point is now manned on the opposite side by a wing of Al Qaeda.

Al Nusra has been making its way northward along the Israeli-Syrian border for a while now. But the regime's loss of Quneitra, and its failure to return there, is particularly striking. Quneitra is a symbol. It was a relatively big city, a regional capital, and it was completely destroyed in the 1967 war. The Syrian government rebuilt a different Quneitra a few miles back from the line, but it left the ruins of the old city as a monument to Zionist aggression. The Assad regime used to take foreign visitors there. As someone remarked to me today, it played a role in the regime's legitimizing of its struggle not unlike the one that the Yad Vashem Holocaust memorial plays for Israel. And now it's in the hands of rebels. Indeed, this border is really now an Israeli-Al Qaeda border.

I have not a shred of sympathy for the Assad regime. When you kill hundreds of thousands of your own people, even calling you the lesser of two evils is a kind of flattery I won't engage in. Yet there is something alarming about the notion that one of our allies now has a border with Al Qaeda.

So far, the Al Nusra Front has not sought to launch any attacks on Israel. And Israel is loathe to interfere in the Syrian conflict, so it has basically watched as its long-time state enemy has been replaced with a wing of the Syrian rebels that pledges allegiance to Ayman Al-Zawahiri. This border has been largely stable for a long time, and it's creepily so now too. There are no rockets coming over the line. The war is not across the line but on one side of it.

But how long will that last? It's impossible not to sympathize---whatever one thinks of Israeli handling of, say, settlements or Palestinian aspirations---with Israeli anxiety about its new neighbor. And there's something deeply unsettling about buying a cup of coffee and looking out over a line, beyond which are lands controlled by Al Qaeda.