By Stephen Collinson, CNN

(CNN) -- Donald Trump has always insisted he's all about winning.

But on Monday night, as he laid out his new strategy for Afghanistan, America got to see how its new President confronted what many experts believe is a no-win situation: a war that has dragged on with no end in sight for 16 years.

Trump laced his prime-time speech with volleys of bold language that might be expected from a new commander-in-chief taking over a failing war.

"Our troops will fight to win. We will fight to win," Trump said. "From now on, victory will have a clear definition. Attacking our enemies, obliterating ISIS, crushing Al-Qaeda, preventing the Taliban from taking over Afghanistan, and stopping mass terror attacks against America before they emerge."

Despite the Churchillian flourish, that definition of America's goals in Afghanistan did not seem that much different to the aims prevailing at any stage of the nation's longest war.

Trump promised to do away with the troop withdrawal timetables favored by his predecessor Barack Obama, and to outlaw "micromanaging" of the conflict from armchair generals back in Washington. He also adopted an old chestnut -- promising to pressure Pakistan to drop support for radical groups.

But his plans hardly seem sufficiently sweeping to unlock the victory that eluded Presidents George W. Bush and Obama in a nation that is treacherous for foreign invaders.

They are also unlikely to significantly change calculations among Taliban leaders and in Pakistan's military intelligence agencies.

In fact, Trump's strategy might be best explained as an attempt to slow an alarming decline in security conditions in Afghanistan and to thwart the specter of a possible defeat on his watch.

It's now less about winning than reaching what the President called "an honorable and enduring outcome."

For political or strategic reasons, Trump did not officially announce his expected dispatch of an extra 4,000 troops to Afghanistan to train and advise Afghan forces and to improve air support to try to mitigate stunning casualty rates among local forces. The figure has been widely leaked.

That may well represent a sound strategy and the best that the public can be expected to bear after exhausting, bloody years of war.

But it appears to fall short of the radical change in approach implied by his speech -- that was, like many Trump addresses, longer on rhetoric than details.

Certainly, there was little to change the basic and confounding equation of America's involvement in Afghanistan -- it's a war that America can't afford to leave, but it's almost impossible after all these years to win.

With that in mind, Trump's address appeared as much about trying to relieve the multiple political pressure points bearing on his beleaguered presidency as laying out a radical correction of military strategy.

He started his speech with an appeal for national unity, justice, patriotism and love of one's fellow Americans, in another attempt to move on from the gales of protests at his handling of violence in Charlottesville, Virginia.

"When we open our hearts to patriotism, there is no room for prejudice, no place for bigotry," Trump said, a week after drawing an equivalence between white supremacists and anti-Nazi protestors.

Any good those sentiments do is likely to be undercut by the irony that Trump, since taking office, and before, has done more to provoke divisions and tear at political and societal fault lines than any almost any other figure.

A chance Tuesday to rally his base

His new unifying tone will also be sorely tested when he walks into the bear pit of a rally in Arizona on Tuesday night, when the teleprompter Trump may be replaced by the freewheeling campaign trail version who can't resist quips and asides that frequently steer him into political strife and alienate all but his loyal political core supporters.

For students of the realigned power dynamics of the Trump White House, Monday's speech was also a sign of the influence of the core of current or retired generals at the heart of the Trump administration -- including Chief of Staff John Kelly and national security adviser H.R. McMaster, who both served in Afghanistan.

Both men, along with top Pentagon brass, have long argued that the US cannot afford to walk away from the war in Afghanistan after the loss of more than 2,300 US troops, more than 1,100 allied soldiers, more than 30,000 Afghan forces and more than 30,000 Afghan civilians.

The question is particularly personal for Kelly, as he lost a son fighting in Afghanistan.

The military has long chafed against the timelines for withdrawal that were preferred in the previous administration. In his first big Afghanistan war speech, Obama promised a surge of 30,000 troops but stipulated they would start coming home within 18 months. The generals believe such artificial deadlines simply encourage enemies to wait America out.

But Trump is already experiencing the other side of the argument -- as he effectively handed Democrats a potent political opening.

"When President Trump says there will be no ceiling on the number of troops and no timeline for withdrawal, he is declaring an open-ended commitment of American lives with no accountability to the American people," said House Minority Leader Nancy Pelosi.

There also remains a real risk that some of Trump's own supporters may balk at his reversal on Afghanistan after his repeated comments about wars without end that closely mirror Pelosi's attack. His speech comes days after the departure of his chief political strategist, Steve Bannon, who opposed sending more troops and is closely aligned with the President's base.

Trump made an effort Monday to explain why he had changed his mind.

"My original instinct was to pull out. And historically, I like following my instincts," Trump said. "But all my life I've heard that decisions are much different when you sit behind the desk in the Oval Office, in other words, when you're President of the United States."

But he also insisted America's staying power is not infinite in Afghanistan -- in some ways undermining his military message.

"The American people expect to see real reforms, real progress, and real results. Our patience is not unlimited," Trump said.

On Tuesday morning, Vice President Mike Pence published an op-ed in USA Today touting Trump's Afghanistan agenda.

"President Trump's strategy for South Asia will undo the failed policies of the past and put the safety and security of the American people first," Pence wrote in the op-ed. "And with the President's leadership, with the courage of our armed forces, and with the prayers of our people: America will be stronger, safer and more secure than ever before."

Pence also planned to appear on several morning news shows to push the message.

Trying to steer a different course from Obama

In another nod to his supporters, Trump indulged the tough on terror persona that helped rile up his campaign crowds.

"We need look no further than last week's vile, vicious attack in Barcelona to understand that terror groups will stop at nothing to commit the mass murder of innocent men, women, and children. You saw it for yourself. Horrible."

At the same time, Trump implicitly appeared to be trying to counter the impression -- voiced by Republicans as well as Democrats in recent days -- that he is simply not up to the intellectual demands of the presidency.

"I studied Afghanistan in great detail and from every conceivable angle," he said, referring to a policy process involving his top generals and national security aides, and complaining he was dealt a "bad and complex" hand when he took office.

Throughout his presidency, Trump has expressed intense antipathy to any course pursued by Obama.

And while he did not, for once, personally rap his predecessor, he piled heavy implicit criticism on Obama for the withdrawal from Iraq -- echoing criticism of many foreign policy experts who believe it created a vacuum exploited by ISIS.

"We cannot repeat in Afghanistan the mistake our leaders made in Iraq," Trump said, though avoided mentioning that he also called for US troops to come home from Iraqi battlefields, though later denied he had done so.

But political maneuvering aside, his strategy appeared a lot more like the Obama approach than his speech let on, reflecting the limited options that are left for America's military planners after such a long conflict.

In the end, his speech may also represent a lesson about the presidency, whether Trump is ready to learn it or not.

Winning is really hard. And sometimes presidents just have to settle for not losing.