FILE - Acting U.S. Secretary of Defense Christopher Miller stands on the steps of the Pentagon entrance in Arlington, Virginia, Nov. 13, 2020.
FILE - Acting U.S. Secretary of Defense Christopher Miller stands on the steps of the Pentagon entrance in Arlington, Virginia, Nov. 13, 2020.

WASHINGTON - Acting Secretary of Defense Christopher Miller struck a contradictory tone about the U.S.-led global war on terror in his first letter to the department, amid heightened concerns that big defense policy changes might emerge during President Donald Trump’s final weeks in office.
 
"This war isn't over. We are on the verge of defeating al-Qaida and its associates, but we must avoid our past strategic error of failing to see the fight through to the finish," Miller wrote in a letter dated Friday.
 
However, in the very next paragraph Miller wrote, “We met the challenge; we gave it our all. Now, it's time to come home.”

Experts, along with current and former senior military officials, have raised concerns about the timing of the appointment of Miller, who replaced Mark Esper this week. They warn the move has created the perception of instability and could lead to hasty military policy moves.
 
“During the next couple months, we need leaders at the Pentagon who are willing to push back on any bad ideas emanating from the White House and to work closely with President-elect [Joe] Biden’s transition team,” Bradley Bowman, senior director of the Center on Military and Political Power at the research group Foundation for Defense of Democracies, told VOA.
 
Among the concerns are President Trump’s desire to remove all of the approximately 4,500 U.S. troops serving in Afghanistan, where the U.S. has been fighting for nearly two decades to prevent al-Qaida and other terror groups from establishing a safe haven, where they can carry out attacks on the U.S. and its allies.
 
Miller’s newly appointed senior adviser, retired Army Col. Douglas McGregor, has called for a complete withdrawal of U.S forces from Afghanistan, along with shutting down the U.S. Embassy in Kabul.
 
“I do think we will regret a hasty withdrawal from Afghanistan — not only because of what it will do to our Afghan and coalition partners, but also because of what it will signal about our strategy and role as a leader,” a former senior military official told VOA Friday.
 
A U.S. official, speaking on the condition of anonymity, says a speedy, hastened withdrawal from Afghanistan in a few weeks would be "costly and much more dangerous," than a slower, more deliberate withdrawal based on the security conditions on the ground.
 
The official added that hundreds of millions of dollars in U.S. equipment currently in the country hangs in the balance of such a move, with some equipment needing to be turned over to Afghan forces, some equipment having to be evacuated from the country for security purposes, and some equipment needing to be destroyed.
 
Last month, Trump tweeted that the U.S. should have its troops, who are serving in Afghanistan, home by Christmas.

Shortly afterward, Trump’s national security adviser said the president’s tweet that all U.S. troops should be home from there by December 25 was a “desire” rather than a military order.
 
“Right now, we're on a path with our European allies — we went into Afghanistan together; we're going to come out together — we’re on a path right now that looks like about 4,500 this fall and a smaller number in January and February,” national security adviser Robert O’Brien said on October 16.
 
Miller, the former Director of the National Counterterrorism Center, was appointed acting secretary of defense Monday after outgoing President Donald Trump abruptly fired Defense Secretary Mark Esper. The move was announced in a surprise tweet on social media shortly after Trump’s chief of staff, Mark Meadows, called Esper to inform him of his termination, an official told VOA.

Esper had been expected to serve through the transition period between now and President-elect Joe Biden’s inauguration on January 20, 2021, although rumors of his imminent firing had been swirling around Washington for weeks.  
 
In a final message to the Defense Department late Monday, Esper touted the progress made on implementing the National Defense Strategy, which shifted the Pentagon’s focus toward modernization and efficiency in light of near-peer competition with Russia and China.
 
“Stay focused on your mission, remain steadfast in your pursuit of excellence, and always do the right thing. Following these imperatives will ensure you remain the most ready, respected, and capable military force in the world,” he wrote.
 
Trump and Esper’s relationship reportedly had been tense since a rift in June. Days after the president threatened to deploy active-duty forces to quell protests against police violence and racial injustice, Esper publicly declared his opposition to any such move.
 
Esper expressed frustration with the nickname “Yesper,” which he was dubbed by critics, including the president, telling the Military Times newspaper in an interview on November 4 that he preserved his integrity during his tenure without being anyone’s “yes man.”
 
“At the end of the day … you’ve got to pick your fights,” he said in the interview. “Why? Who’s going to come in behind me? It’s going to be a real ‘yes man.’ And then God help us.”
 
Esper served as defense secretary from July 2019 through November 9, 2020.
 
VOA national security correspondent Jeff Seldin contributed to this report.