Retired Admiral James Winnefeld says President Trump has devised a "reasonable way forward" in the administration's strategic plan for the war in Afghanistan.

"This was about the transition from shrill and simple rhetoric on a campaign trail, into sort of adult, grown-up decisions on very complicated national security problems, I give him little bit of credit for actually listening to national security advisers, not just the military but the full spectrum of advisers," said Winnefeld on "CBS This Morning" on Tuesday.

During Monday evening's speech to members of the military at Fort Myer in Arlington, Virginia, Mr. Trump explained his change of heart on the U.S.'s 16-year-long battle in Afghanistan.

"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," the president said in his primetime address to the nation. "My original instinct was to pull out and historically, I like following my instincts."

Winnefeld, who served as vice chairman of the Joint Chiefs of Staff in the Obama administration, called Mr. Trump's reversal a "stunning admission that he had changed his mind."

"It gave me a sense that there are some areas he's probably outflanked in expertise and he really needs to listen to these people, and I do think he asked the right questions, which is a president's responsibility to do," said Winnefeld.

Winnefeld noted Mr. Trump's plans include "minor changes to existing policies" but provide a "sustainable counter-terrorism approach to Afghanistan."

Meanwhile, as NATO leaders have appeared to support Mr. Trump's strategy in Afghanistan, Winnefeld said allies would agree that a difficult step forward in the process would be in applying diplomatic pressure on Pakistan.

"Of all of our many allies, Pakistan is one of the most difficult. In South-Asian culture they will undermine you at same time they support you."

Winnefeld said "the real room for diplomacy is to makes sure that NATO partners are onboard" as well as add "intense pressure on Pakistan to step up a little more than they have been."

Winnefeld said he would not advocate a full withdrawal from the region, and he said the president was clear in his speech that "our ends, ways, means, balance of strategy remain intact there" and that Mr. Trump recognized it's "very clear those threats still exist" in the region.

"There really is no crisply defined end state which we as Americans love to have," said Winnefled, saying Americans would like to hope for a sustainable Afghan government free from the threat of terrorists.

"In fact, the end state would be that there's no attacks conducted on this country from that nation."