Former Defense Secretary Jim Mattis acknowledged Sunday that U.S. troops could be demoralized by orders to withdraw from northern Syria that force them to leave behind allies who continue the fight.
When asked about the impact on military morale from the pullouts, Mattis said on NBC's "Meet the Press" that "we have to always be concerned with this."
The Syrian Democratic Forces, who fought alongside U.S. troops in the battle against ISIS, now must face the invading Turkish military in the wake of U.S. withdrawal.
"We have got to have policies that make sense on the front line [and] ... in terms of the defense of the country," Mattis said.
The retired Marine general did not refer directly to statements U.S. troops on the ground in Syria have made to several news outlets, regarding a sense of shame they feel in being seemingly being ordered to abandon the SDF.
"I am ashamed for the first time in my career," an unidentified soldier in Syria who has been involved in training the SDF told Fox News Wednesday. "Turkey is not doing what it agreed to. It's horrible."
Mattis said that trust was essential in partnering with local forces.
"Re-instilling trust will be difficult for Americans at this point" if they seek to continue partnering with the mostly-Kurdish SDF against ISIS, he said.
Turkey considers the Kurdish YPG (People's Protection Units), the main fighting force within the SDF, to be a terrorist organization, but Mattis noted the sacrifices of the SDF in the long and bloody campaign to drive ISIS from its territorial strongholds in Syria.
In the campaign with the SDF against ISIS, the U.S. has lost about a dozen troops -- "each one a tragedy" -- while the SDF "has lost well over 11,000 killed and 23,000 wounded," Mattis said.
He called the Kurdish fighters in the SDF a "like-minded ally," and said "the Kurds are carrying the brunt of the battle."
Unless the U.S. can re-establish trust with the SDF, a resurgence by the Islamic State was inevitable, Mattis said.
"We may want a war over, we may even declare it over," he said. "You can pull your troops out as President [Barack] Obama learned the hard way out of Iraq, but the 'enemy gets the vote' -- we say in the military."
He referred to the 2011 drawdown in Iraq ordered by Obama, and backed by then-Iraqi Prime Minister Nouri al-Maliki, which has been criticized for setting the stage for the emergence of the ISIS threat.
"And in this case, if we don't keep the pressure on, then ISIS will resurge," Mattis said. "It's absolutely a given that they will come back."
Mattis' appearance on "Meet the Press" was part of an ongoing promotional tour for his book "Call Sign Chaos: Learning to Lead."
Mattis, who resigned as Defense Secretary last December following Trump's surprise announcement that he intended to withdraw all U.S. troops from Syria, has carefully worded his statements since then to avoid direct criticism of Trump.
However, Mattis said on "Meet the Press" that "ISIS is not defeated," despite Trump's repeated statements that ISIS has been "100%" destroyed.
-- Richard Sisk can be reached at Richard.Sisk@Military.com.