President Trump memorialized the men and women who have died serving the United States in the military on Monday, citing Homeland Security Secretary John Kelly's late son as one of the people Americans remember on Memorial Day.

"He [Kelly] and his incredible wife, Karen, have borne the single most difficult hardship of them all, the loss of their son, Robert, in service to our country," Trump told attendees during his speech at Arlington National Cemetery on Monday. Kelly's son died in Afghanistan.

"The Kelly family represents military families across the country who carry the burden of freedom on their shoulders. Secretary Kelly is joined today by his son-in-law Jake, a wounded warrior, and the secretary's son, Johnny, who will soon leave on his fifth deployment," Trump added. "It is because of families like yours that all of our families can live in safety and live in peace."

Below overcast skies, a somber Trump linked the Kelly family's service to sacrifices made by the other Gold Star families in the crowd.

"To every Gold Star family who honors us with your presence, you lost sons and daughters, husbands and wives, mothers and fathers, they each had their own names, their own stories, their own beautiful dreams. But they were all angels sent to us by God," Trump said. "And they all share one title in common, and that is the title of hero. Real heroes. They were here only a brief time before God called them home. Their legacy will endure forever."

Trump commemorated three members who gave their lives in recent deployments, including Army Spc. Christopher D. Horton and CPT Andrew Byers of the 10th Special Forces Group.

"I believe that God has a special place in heaven for those who lay down their lives so that others may live free from fear and this horrible oppression. Now let us pledge to make the most of that freedom that they so gallantly and so brilliantly fought for, and they died to protect," Trump added.

Trump also praised audience member former Sen. Bob Dole, R-Kan., who served in World War II, and others for their service.