President Trump unveiled what he described as a "dramatically" new U.S. strategy in Afghanistan and South Asia Monday night, but declined to provide specific details about a possible increase in troops.

The plan does not involve a withdrawal of U.S. troops from America's longest-running war, the president said, though he admitted that pulling the military out was his initial instinct.

"I share the American people's frustration. I also share their frustration over a foreign policy that has [spent] too much time trying to rebuild countries in our own image instead of pursuing our security interests," he said in a primetime address to the nation from Fort Myer in Arlington, Virginia. "My original instinct was to pull out and historically, I like following my instincts."

Indeed, Mr. Trump had for years protested that it was time for the U.S. to leave Afghanistan -- here's one of his tweets from 2013, in which he said, "Let's get out of Afghanistan."

But after meeting with Defense Secretary James Mattis, and other members of his national security team, he said he arrived at a difference conclusion.

HIGHLIGHTS: The president said that there are three pillars to his strategy:

  • The U.S., he announced, will shift from a "time-based approach to one based on conditions" in which he said his administration will "not talk about numbers of troops" or plans for further military operations. He said that "conditions on the ground, not arbitrary timetables, must guide our strategy from now on."
  • Mr. Trump said that Afghanistan will require the integration of diplomatic, economic and military solutions in which one day, a political settlement could occur that might involve elements of the Taliban.
  • The president said that the U.S. must change its approach on how to deal with Pakistan, which he said provides safe havens for terrorists.

The president added that the U.S. must further develop its relationship to India so that it can help with economic assistance to Afghanistan.Mr. Trump emphasized that the U.S. would no longer engage in "nation-building" overseas and is instead mainly interested in decimating terrorist groups and defending the U.S. from national security threats.

The president vowed not to engage in a rapid exit from Afghanistan, whose consequences, he said, would be "predictable and unacceptable." He said that it would create a "vacuum" that terrorists like al Qaeda and ISIS would instantly fill. Mr. Trump  criticized the Obama administration for the 2011 decision to "hastily"  withdraw from Iraq.

While Mr. Trump did not explicitly say that the U.S. is sending additional troops to Afghanistan, he certainly hinted at it. The president said that he will ask NATO partners for additional troops and funding increases in Afghanistan "in line with our own."

He also made clear, "Our commitment is not unlimited and our support is not a blank check," he said. Mr. Trump said that the Afghan government must carry its share of the military and economic burden. 

In Afghanistan, 8,400 U.S. troops remain, down from a high of 100,000 during President Obama's first term.

The administration had been exploring possible options for a new strategy for months, but the decision was delayed over concerns that the U.S.-led coalition is not winning the fight against the Taliban, al Qaeda and the Islamic State in Iraq and Syria (ISIS). 

In June, CBS News national security correspondent David Martin reported that the Pentagon had been making plans to send additional U.S. troops to Afghanistan, with the number expected to be between 3,000 and 5,000 troops. 

The Trump administration had also been considering a plan proposed by Blackwater founder Erik Prince to privatize a large portion of the U.S. effort in Afghanistan in which 5,000 private military contractors would replace U.S. troops that assist the Afghan army.

The president has been pulled in two directions. The U.S. military has pushed for more Special Operations fighters, fewer battlefield restrictions and no timetable for withdrawal. On the other side, ousted chief White House strategist Steve Bannon pushed for a complete U.S. pullout, arguing that Afghanistan was no longer a vital U.S. interest. As far back as 2011, Mr. Trump has argued that Afghanistan has been a waste of tax dollars.

Mr. Trump's address comes after he's spent two weeks at his golf club in Bedminster, New Jersey, and experiencing the most tumultuous week in his presidency last week after the way he handled the terror attack and violence ignited by white supremacists in Charlottesville.