President Trump articulated important truths about military interventions and pronounced fine principles about the use of force. But he also suggested an open-ended commitment in Afghanistan and articulated an incoherent notion of victory.

Trump, whose views on war and foreign policy have been inconsistent over the years, started to form something of a coherent foreign policy over the course of the campaign, the transition, and his first few months in office. Former President George W. Bush's Iraq war was a mistake, Trump said, because throwing out Saddam Hussein destabilized the region. He made a similar argument about Former President Barack Obama's regime change in Libya.

The rise of ISIS and the continued chaos in Libya and Iraq seem to have confirmed the wisdom of this disposition against regime change. But, as Trump said, "We do not have the luxury of going back in time" to undo past wars, and this mindset that tells you not to attack and overthrow a government doesn't tell you what to do when you've already attacked and overthrown the government.

The fog of war makes it too difficult to say with confidence what America's best course of action would be in Afghanistan, a country we invaded in 2001, when some of today's soldiers were in diapers. But this is clear: What we're doing now isn't working.

"We're not winning in Afghanistan right now" was the plain and sober assessment earlier this year by Defense Secretary James Mattis, a retired general.

But coming out of Trump's speech Monday night, we still don't know what course of action he has planned, and we're not sure if the military does. The principles Trump articulated seem disconnected from his plan.

"We are not nation-building," he said. "We will no longer use American military might to construct democracies in faraway lands." These are sensible principles and welcome departures from the misguided ideology of our past two presidents. But Trump said these things while pledging thousands of additional troops to Afghanistan for an indefinite amount of time.

What is the aim? What would victory look like? He said "we are killing terrorists," but he cannot believe that we can kill every terrorist in Afghanistan. He suggested we would try to instill "stability" in Afghanistan, but that sounds a lot like nation-building.

Trump has an argument for his open-ended time period: not wanting to repeat Obama's mistake. In his 2009 speech at West Point, pledging 30,000 more troops to Afghanistan, Obama said he would start pulling troops out in 2011. Promising to leave a hotbed of terrorists and scumbags at a date certain just tells the extremists they can wait you out. The mess that is Afghanistan today testifies to that folly.

Trump sensibly said our parameters would be "conditions," not dates. But the conditions of stability and no more terrorists are not attainable in Afghanistan, which has been dysfunctional for more than just one generation.

Trump and Mattis need a clearer goal, something between let it descend into chaos and stability. Without a clearer, attainable goal, Trump is sending men off to kill and die in a war where victory is unattainable.