President Biden and first lady Jill Biden thanked U.S. service members overseas during a call on Saturday while also expressing sadness that the troops could not celebrate Christmas at home with their families.

President Biden, alongside the first lady and their new dog, Commander, named the countries service members were calling in from — Bahrain, Qatar, Romania — before adding, “Everywhere but home. Sorry.”

“We are sorry. You know, one of the things we know because we are a military family, we know what it’s like to have you, you know, our loved ones serving and being away during the holidays, and so I’m sorry you have to be away. We know what it’s like for your families to have that empty seat at the table like we had,” the first lady added.

President Biden’s son Beau Biden served in Iraq for a year, and the first lady’s father served as a signalman in the South Pacific during World War II.

The first couple’s call with service members was their first and likely only public appearance on Christmas Day. They took questions from troops off camera after delivering brief opening remarks.

The Bidens are having a quiet Christmas at the White House with their family after visiting Children’s National Hospital on Christmas Eve. They did, however, release a Christmas message to the nation, pointing to the “courage, character, resilience, and resolve” of Americans in a year that was marked by the pandemic.

The first lady, during remarks to the overseas service members, said she and the president “certainly know as a family what your families are feeling today, and that’s why we will continue, Joe and I will continue, forever and ever to support you in any way we can but most of all serve your families.”

The president emphasized the hardship felt by families of service members on the holiday.

“I know, as Jill said, you’d rather be home today, and I don’t blame you. Jill and I know how hard it is for you, but, quite frankly, it’s harder for your husbands, wives, moms, dads, children [to] be apart or on on duty during a season of togetherness, and we Bidens understand that,” he said.

“We still every once in a while look at that empty chair,” he added, likely referring to Beau Biden’s death in 2015 following a battle with brain cancer.

President Biden thanked the service members for their service but called the expression of gratitude “a poor substitute for what you’re missing.”

“I understand. I just want you to know how much we care. We’re grateful for your courage, your sacrifice, not only your sacrifice but your family’s sacrifice,” he said.

“The holidays really bring into sharp focus [that] being apart is, it’s just part of the job, but it’s a hard part of the job,” he added, before calling the service members “the solid steel spine of the nation.”

The president said the only “truly sacred obligation” of the U.S. is to “properly prepare those and equip those who we send into harm’s way and to care for you and your families while you’re gone and when you return home.”

“Because all of you are out there doing what you’re doing, Americans all across the nation are able to spend the day with their loved ones enjoying the blessings of security of our American democracy, and we’re so, so grateful,” he added.