PHILADELPHIA — Flanked by a platoon of retired military leaders and recent war veterans, retired Marine Gen. John Allen addressed the Democratic convention in Philadelphia Thursday to back former Secretary of State Hillary Clinton as the best choice to keep America secure in years to come.

"We trust her judgment," said Allen, who led troops in Iraq and Afghanistan and served as the country's top envoy in the fight against the Islamic State group. "We believe in her vision for a united America and we believe in her vision of America as the just and strong leader against the forces of hatred, chaos, and darkness.

"We know that she as no other knows how to use all instruments of American power — not just the military — to keep us all safe and free."

The endorsement, previewed by campaign officials on Monday and touted by party leaders throughout the week as evidence of Clinton’s national security prowess, was the latest in a sizeable line of veteran speakers at the week-long event.

A day earlier, Defense Secretary Leon Panetta offered his public support for Clinton, calling her the most qualified candidate ever to step into the White House. Moments after Allen's endorsement, retired Army Capt. Florent Groberg — who earlier this year received the Medal of Honor for valor in Afghanistan — offered similar praise for Clinton.

"She has been training for this moment for decades," he said. "In the Senate, she worked across the aisle to support wounded warriors and our families. As president, she'll reform the VA, not privatize it. And as commander in chief, she will defeat ISIS."

Retired US Army Captain Florent Flo Groberg addresses delegates on the fourth and final day of the Democratic National Convention at Wells Fargo Center on July 28, 2016 in Philadelphia, Pennsylvania. Groberg was awarded the Medal of Honor, the nations top award for valor in combat, by President Obama after serving in Afghanistan. / AFP / SAUL LOEB (Photo credit should read SAUL LOEB/AFP/Getty Images)
Retired US Army Captain Florent Flo Groberg addresses delegates on the fourth and final day of the Democratic National Convention at Wells Fargo Center on July 28, 2016 in Philadelphia, Pennsylvania. Groberg was awarded the Medal of Honor, the nations top award for valor in combat, by President Obama after serving in Afghanistan. / AFP / SAUL LOEB (Photo credit should read SAUL LOEB/AFP/Getty Images)

Retired Army Capt. Florent "Flo" Groberg addresses delegates on the final day of the Democratic National Convention on July 28, 2016, in Philadelphia.

Photo Credit: Saul Loeb/AFP via Getty Images

Allen’s endorsement of Clinton was notable not only for his status as a respected former Marine Corps leader, but also because of his known friction with President Barack Obama.

The two sparred over the speed of the drawdown of troops from Afghanistan, and Allen abruptly quit his ISIS envoy post in September 2015 amid reports he disagreed with defense officials about the strategy to defeat the terrorist group.

But the retired four-star general unequivocally backed Clinton as a leader who will keep America as an "indispensable, transformational power" for the world.

"We will lead and strengthen NATO … and America will stop the spread of nuclear weapons and keep them from dangerous states and groups," he said. "Our armed forces will be stronger. They will have the finest weapons and equipment.

"They will have the support of the American people, and the American military will continue to be the shining example of America at our very best."

Allen's speech also included a number of thinly-veiled shots at Republican presidential nominee Donald Trump without naming him.

"With her as our commander in chief, our international relations will not be reduced to a business transaction," he said. "Our armed forces will not become an instrument of torture, and they will not be ordered to engage in murder or carry out other illegal activities."

Last week, at the Republican convention in Cleveland, Trump advisoer and former Defense Intelligence Agency director retired Lt. Gen. Michael Flynn gave a starkly different take on the presidential election, label Clinton as an "Obama clone" who will follow the same failed foreign policy decisions.  

"Under Barack Obama, we have no coherent strategy to protect our citizens, and under Hillary Clinton, it will be more of the same," he said.

National security is expected to remain a key focus of the remaining months of the presidential campaign, with both candidates promising solutions to defeat ISIS and secure the homeland against foreign terrorist attacks.

Leo Shane III covers Congress, Veterans Affairs and the White House for Military Times. He can be reached at lshane@militarytimes.com.