In his Monday speech on Afghanistan, President Trump admitted something he's rarely faced up to: Decisions are "much different" when you are president than in the heat of a campaign.

The president's original instinct, expressed repeatedly over the years, was to pull any remaining troops out of Afghanistan. The public is understandably tired of America's longest war, which has dragged on for nearly 16 years. There are no good military options in sight.

Yet after a policy review that dragged on for seven months and bitterly divided the White House, the president finally faced up to grim reality: A full retreat from Afghanistan meant al-Qaeda and ISIS would find havens again as the Taliban seized more swaths of the country.

So Trump finally went with the advice of his generals, including national security adviser H.R. McMaster, to boost the current 8,400 troops by at least another 4,000 (some of the brass wanted more).

Needless to say, those numbers alone don't offer a promise of reversing the current Taliban resurgence. But Trump's new policy, though vague and marked by some glaring holes, contained several shifts in direction that could make a difference on the ground.

Let's call those directional shifts the four "Nos."

The first No is no deadline for troop withdrawal. President Barack Obama made a huge error when he surged troops in Afghanistan in 2009 but announced in advance the date for their pullout.  The Taliban just waited him out, as did Afghanistan's mischief-making neighbor Pakistan (see below).

Given the small number of U.S. troops — and their primary role as trainers — it makes more sense to see their presence as part of a long-term investment in order to prevent a terrorist resurgence. Their presence also reminds regional neighbors Iran, Russia, India, and Pakistan that America is still paying attention.

The second  No refers to no more efforts at nation-building. We tried that and failed.

The few thousand remaining U.S. troops will focus on training Afghan special operations forces and commandos, and, learning from lessons in Iraq, on calling in air and artillery strikes to support Afghans. This is how a limited number of U.S. troops helped the Iraqi army finally defeat ISIS in Mosul.

The third No is the apparent veto of a bizarre idea the president toyed with: to hire Erik Prince, founder of the notorious Blackwater private contractor outfit that shot up Baghdad, to lead a mercenary force replacing U.S. troops in Afghanistan.

Most important is the fourth No: No more havens for the Afghan Taliban in Pakistan. The Pakistani military and intelligence services have long played a double game, warring on Pakistani Taliban that attack their own military and civilians while giving haven to Afghan Taliban leaders and fighters. The Pakistanis have also hosted other Islamist terrorists who attacked India, and they harbored Osama bin Laden for years.

Islamabad plays this double game because it views the Afghan Taliban and other terrorist groups as vital tools in its endless struggle against India. Both the Bush and Obama administrations tried fruitlessly to persuade Pakistan with financial carrots to shut down these terrorist havens.

McMaster is known to have sought a tougher line on Pakistan. And Trump proclaimed, "We can no longer be silent" about Pakistani havens for terrorists. The success of any Trump policy on Afghanistan may depend on whether his team can figure out how to change Pakistan's behavior.

Which brings me to the big holes in Trump's "strategy."

The president paid lip service to diplomacy, saying his policy would "integrate all instruments of American power." But the troubled State Department has been denuded of expertise on South Asia, and the president's words made clear his skepticism about diplomatic efforts.

Trump repeatedly promised to "win" in Afghanistan and called for "outright victory." Afghanistan's history shows that "victory" within its borders is a dubious hope.

Ultimately, the point of military progress in Afghanistan would be to provide muscle behind a diplomatic push in the region — aimed at persuading all of Afghanistan's neighbors that its stability is in their interests and that they should stop backing factions on its soil.

Short of that, the best U.S. hope may be to prevent ISIS or al-Qaeda from establishing new bases, which would require a long-term U.S. presence and focus. Continued bluster about swift and outright victory will only make Americans antsy.

Afghanistan is Trump's war now, and it will require the kind of long-range thinking he hasn't demonstrated up until now.