President Trump on Monday night will announce a “path forward” on military strategy in Afghanistan, offering his imprint on the longest-running war in U.S. history — and one in which a lack of progress has increasingly frustrated the new president.

Trump is scheduled to address the military and American people from Fort Myer in Arlington, Va., White House press secretary Sarah Huckabee Sanders said in a brief statement Sunday afternoon.

The nationally televised prime-time address offers Trump an opportunity to seize the mantle as commander in chief on a key foreign policy issue at a time when his standing at home has been undercut by his widely repudiated statements about last weekend’s violence in Charlottesville.

He has also faced major staff upheaval and tense relations with key members of the Republican president’s own party.

Various options have been under consideration for Afghanistan, including sending about 3,800 more troops to augment the 8,400 already there to train and assist local forces.

Defense Secretary Jim Mattis talks with Chief of Staff of the Army Gen. Mark A. Milley, left, at the White House in July. (Jabin Botsford/The Washington Post)

Another option Mattis has mentioned is to replace U.S. troops with private contractors.

But any proposal to reinforce the U.S. presence there is certain to meet resistance.

Sen. Benjamin L. Cardin (Md.), the ranking Democrat on the Senate Foreign Relations Committee, said on “Fox News Sunday” he would oppose sending more troops. “I don’t believe putting more American soldiers in Afghanistan is the answer,” he said, arguing a stable government in the country should be the goal.

Sen. Tim Kaine (D-Va.) said Sunday many lawmakers have withheld any judgment on troop levels until they hear the administration’s strategy.

“The troop strength question is sort of the cart before the horse,” Kaine told CBS’s “Face the Nation” on Sunday. “The real question is what is our strategy? And then when you lay out the strategy, the troop strength question can kind of answer itself.”

Earlier Sunday, Defense Secretary Jim Mattis confirmed Trump had settled on strategy.

Speaking to reporters on a military plane en route to meetings in Jordan, Mattis offered no details of the revised U.S. policy. The results have been delayed amid concerns that, more than 15 years after the United States invaded, an international coalition working together with Afghan forces are not winning the fight against the Taliban and al-Qaeda. “I am very comfortable that the strategic process was sufficiently rigorous and did not go in with a preset position,” Mattis told reporters.

Trump met Friday at Camp David with more than a dozen aides, including Mattis, Secretary of State Rex Tillerson, national security adviser H.R. McMaster and Vice President Pence. After the briefing, White House press secretary Sarah Huckabee Sanders said Trump was “studying and considering his options.” Then Trump tweeted Saturday that at Camp David, “many decisions [were] made, including on Afghanistan.”

Trump’s reluctance to commit to a new strategy to this point has reflected the paucity of good options. It also highlights a contradiction at the core of Trump’s foreign policy. On the campaign trail and in conversations with advisers, Trump has said he wants to win and project strength. But he also has called for ending costly commitments in places such as Afghanistan and the Middle East.

Doug Wilson, a former assistant secretary of defense for public affairs in the Obama administration, said it was encouraging that Trump plans to explain his decision. “The challenge will be to explain the policy in the context of what has been a long-running goal that Afghanistan never be used as a springboard for terrorism against the United States or its allies,” Wilson said.

Ron Bonjean, a Republican strategist who has worked with the White House on other issues, said “the address is designed to turn the page from the Charlottesville chaos and remind voters that Trump is commander in chief and has made an informed and responsible decision.”

Trump has given Mattis authority to set troop levels in the country, but Mattis has been waiting for Trump to decide a strategic focus before he sends any more troops.

Trump has expressed frustration over the lack of a path forward as the war drags into its 16th year. After the attacks on the Pentagon and World Trade Center in 2001, the United States sent in troops to oust the Taliban government because it sheltered the operation’s mastermind, Osama bin Laden. At a Senate hearing in June, Mattis acknowledged, “We are not winning in Afghanistan right now.”

The policy review was expected to be completed weeks ago, and the delay underscores how difficult the decision has been.

As the review dragged on, several other parties weighed in publicly with their visions.

Sen. John McCain (R-Ariz.), the chairman of the Armed Services Committee, offered a plan that would increase troops and further airstrikes. Erik Prince, the founder of the security company Blackwater, has been a leading voice on turning U.S. strategy over to the private sector — a prospect some administration officials have strongly resisted.