If insanity is defined as doing the same thing over and over again while expecting different results, President Trump on Monday night committed the United States to a few more years of madness in Afghanistan.

Don't be fooled by Trumpian bluster about a brand-spanking-new "plan for victory" that will get "results" and finally enable us to defeat the Islamist "thugs" and "losers" of South Asia. What the president has proposed is a troop surge of unspecified size (this follows George W. Bush's "quiet surge" in the fall of 2008 and Barack Obama's own surge less than two years later) combined with a refusal to state when the intensified hostilities will come to an end. This is an explicit declaration of open-ended war for a conflict that, at 16 years and counting, is already the longest in American history.

It would be one thing if the additional troops were being deployed in order to enact some dramatic shift in strategy or tactics that showed reasonable promise of changing the dynamic on the ground. But for all of Trump's assertions to the contrary, there is no sign of that at all.

We will continue to attack the Taliban, al Qaeda, ISIS, and other Islamist groups. They, in turn, will continue to blend into the population and slink across the border into Pakistan for sanctuary when we put pressure on them. And then the terrorists will resume attacks on Afghan and American forces once our guard is down. The only way to stop this pattern is to break it, and that isn't something that Trump's policy has any serious chance of accomplishing. (Given the extreme undesirability of a war with a nuclear-armed Pakistan, this isn't at all a bad thing.)

What will Trump's Afghanistan policy accomplish? Like the policies of Bush and Obama, it will keep us from losing — an eventuality that would culminate in a Fall-of-Saigon moment in which the Taliban sweeps back into Kabul to retake power for the first time since our invasion following the 9/11 attacks. After 16 years, over $700 billion, and more than 2,200 lives lost and 22,000 wounded, that would be an extraordinary humiliation for the United States.

And that illustrates with bracing clarity exactly where this lost, exhausted superpower has ended up 28 years after the conclusion of the Cold War.

The U.S. can project military force across the globe, topple hostile governments at will, and threaten outlaw regimes with nuclear annihilation. But we're incapable of prevailing in the kind of wars we repeatedly choose to wage: asymmetrical battles against insurgencies and other sub-political movements and factions within failed states thousands of miles away from our borders.

The result, over and over again, is a choice between intractable stalemate and outright failure. And since military failures come with steep political (and geopolitical) costs, elected officials and their advisers opt for stalemate, which in an age of the all-volunteer armed forces has proven to be remarkably sustainable over astonishingly long stretches of time. Most people aren't fighting or even know anyone who is, so why not keep muddling through with no end in sight?

The problem is that of course some people are fighting, and the communities from which they come do notice the indecisiveness and the dithering. In 2016 Donald Trump stood out from both the herd of independent minds seeking the GOP nomination and the Democratic frontrunner in highlighting and denouncing America's aimless, slow-bleed policy in Iraq and Afghanistan. Not that he made clear precisely what he would do differently to change course from the foreign policy "disasters" of the Bush and Obama presidencies. Some days it sounded like he'd withdraw from the world in favor of an "America First" agenda; on others he described a major escalation of air power to pound enemy forces into submission. But at least he pointed to the problem.

What no one would have expected from listening to Trump's blistering debate performances and stump speeches was that once in office he would do pretty much exactly the same thing as Bush and Obama.

The reality is that not even Trump's furious verbal volleys and profoundly disruptive behavior since the inauguration have been enough to wrest his administration free from "the blob" — Washington's bipartisan foreign policy consensus in favor of endless war. That this is the case even when there are perfectly reasonable ideas in circulation that point in a different direction and that would also comport quite well with the policy preferences Trump expressed on the campaign trail is more than a little disconcerting.

And that brings us to what may be the most troubling thing about Trump's speech Monday night: not that he's doing something unhinged but that he's adopted exactly the foreign policy that the political establishment prefers — and that will therefore leave his angriest supporters in the lurch.

If we're not careful, the next time they just might end up throwing their weight behind someone even more dangerous in the desperate (but perfectly understandable) hope of finally finding a little bit of sanity in the midst of the madness that now passes for the status quo.