He has repeatedly criticized the Obama administration for revealing its military plans in a number of different areas, including Afghanistan, so Trump's decision to keep certain details under wraps comes as little surprise.
Here is a rundown of the five biggest takeaways from Monday night's speech.
1. The US military will maintain its presence in Afghanistan
"Our nation must seek an honorable and enduring outcome worthy of the tremendous sacrifices that have been made, especially the sacrifices of lives," he said. "The men and women who serve our nation in combat deserve a plan for victory. They deserve the tools they need and the trust they have earned to fight and to win."
2. We don't know how many more troops will be sent
Trump suggested that more resources will be sent to Afghanistan but did not disclose specifics on how many troops that could involve.
"We will not talk about numbers of troops or our plans for further military activities," he said. "Conditions on the ground, not arbitrary timetables, will guide our strategy from now on."
3. There is no set timeline, at least not publicly
"America's enemies must never know our plans or believe they can wait us out," he said. "I will not say when we are going to attack, but attack we will."
4. A reversal from Trump's earlier stance
Before running for office, Trump repeatedly called for the U.S. military to withdraw from Afghanistan, and he acknowledged the about-face Monday.
"My original instinct was to pull out. And historically, I like following my instincts," he 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."
He said he "studied Afghanistan in great detail and from every conceivable angle" and met with his Cabinet and the generals who are a part of his administration before making a decision.
"The consequences of a rapid exit are both predictable and unacceptable," he said.
5. A focus on Pakistan
One aspect of Trump's new strategy, he said, is "to change the approach in how to deal with Pakistan."
"Pakistan has much to gain from partnering with our effort in Afghanistan. It has much to lose by continuing to harbor criminals and terrorists," he said.
Trump said Pakistan "has been a valued partner" but also noted that it "has also sheltered the same organizations that try every single day to kill our people. We have been paying Pakistan billions and billions of dollars at the same time they are housing the very terrorists that we are fighting. But that will have to change. And that will change immediately."