Wednesday night’s debate didn’t deal much with foreign policy, but one of Donald Trump’s points about the war against ISIS cannot be ignored. He said, as he has before but not at such length, that America’s leaders were stupid to “announce” that they were going to invade Mosul, Iraq. “What happened to the element of surprise?” Trump asked. The leaders of ISIS have long gone, because we’ve warned them, and so the assault will be for naught.

This is nonsense on a few levels.

First, given the basic geography, it is impossible to mount an assault on Mosul by surprise. There is no way to assemble 40,000 troops and suddenly mad-dash into a city of 2 million people, with no advance, and—unavoidably—visible preparation. There is especially no way to do so when—for political as well as military reasons—these 40,000 troops consist of Iraqi soldiers and police, Kurdish peshmerga, Sunni tribesmen, Shiite militias, and American special forces, air power, and intelligence, all with Turkish assent.

Second, the main reason it’s taken so long to prepare this assault is that all those factions had to work out who does what—and who gets what afterward (a negotiation that was prodded and negotiated, by the way, by America’s “stupid” leaders). War is politics by other means, as Clausewitz famously wrote, and the outcome of this war—in particular, this assault on Mosul—will be determined as much by what kind of peace follows: how territory, resources, and power will be shared in what has long been one of Iraq’s few large, multiethnic cities.

Third, Mosul hasn’t been the locus of ISIS leaders for quite a long time, so it’s wrong to say the leaders have fled because they’ve been tipped off about the offensive. The point of the assault is not to kill or capture the leaders—many of whom are in Raqqa or moving around elsewhere in Syria—but to strip ISIS of its territory, to destroy its pretense of a caliphate.

Trump even said, at one point, that the invasion of Mosul is taking place now to make President Obama look good and thus help Hillary Clinton win the election. This is parochialism raised (or lowered) to a new level. If Trump really believes that the Iraqi government, the Kurds, Sunni tribesmen, and Shiite militias have gone to the immense trouble, and taken the near-unprecedented step, of fighting for the same goal in a coordinated operation—something that hasn’t happened since ISIS took Mosul, as its first great gain, two years ago—then he knows nothing about the Middle East, nothing about the struggles of coalition warfare, nothing about global or regional politics, nothing about war.

But that was already clear.

Read more Slate coverage of the 2016 campaign.