WASHINGTON (AP) — Anyone who wants to be president should not “pop off about going to war” because it is serious business, Michelle Obama said Friday as she reflected on the “sobering experience” of visiting wounded patients at military hospitals.

In the early years of President Barack Obama’s tenure, the first lady said their hospital visits would last for hours as they visited dozens of patients, including many who had lost limbs or had suffered other devastating injuries.

“And that’s something that a commander in chief thinks about before they pop off about going to war, because when you’ve spent time on a base and you know these men and women and you know their families you don’t just talk about war like there are no implications,” Mrs. Obama said during an appearance with former first lady Laura Bush at the National Archives.

Less than eight weeks out from the presidential election, Mrs. Obama’s comments were viewed as a direct criticism of Republican candidate Donald Trump, who has said he would “bomb the hell out of ISIS,” also known as the Islamic State group. Trump’s Democratic opponent, Hillary Clinton, has said he cannot be entrusted with the codes needed to launch America’s nuclear arsenal.

Mrs. Obama used the same “pop off” language later Friday as she headlined her first campaign rally for Clinton.

War is “serious business and lives are changed forever,” Mrs. Obama said at the Archives, “so I would hope that any commander in chief that would have the privilege of serving would understand that these are real lives and real families that are impacted.”

She said Obama’s most recent hospital visit was considerably shorter because fewer service members are being injured, “and that feels good.” U.S. troops are no longer engaging in direct combat in Iraq, and Obama is winding down the U.S. military role in Afghanistan.

Mrs. Bush said presidents aren’t the only White House occupants who worry when troops are sent into harm’s way; first ladies agonize, too.

“You worry in the White House when you know that there are troops in harm’s way, and you think about them every single night when you get in bed,” she said. “And there, where you’re in the lap of luxury, really — beautiful house where your sheets are changed every single day — I mean, it really couldn’t be more luxurious — and you think when you get in bed about our troops are laying out on the ground somewhere.”

“So I would say that the main thing about having troops in harm’s way when you live there is that you worry about them all the time, every single day,” Laura Bush said.

The current and former first lady discussed their support for U.S. service members, veterans and their families during a conference sponsored in part by American University. The conversation was moderated by Bob Woodruff, the ABC News anchor who suffered a serious head injury in Iraq when a bomb exploded in January 2006 during the war there.

Mrs. Obama started the Joining Forces military initiative in 2011 with Jill Biden, Vice President Joe Biden’s wife. Laura Bush and former President George W. Bush support service members and veterans through the Bush Institute.

Both women called for more awareness around veterans’ mental health issues.

Mrs. Bush referred to “post-traumatic stress,” not the more common “post-traumatic stress disorder.” She said “it’s an injury, it’s not a disorder.” Mrs. Obama said military members and veterans can raise awareness and help eliminate the stigma by being “brave enough” to get help.

Asked whether they would stay involved with the issue, Mrs. Obama jokingly replied: “Absolutely. What else are we going to do?”

Laura Bush said the issues first ladies champion are ones that must be worked on continually, and that it’s great to have a platform as a former first lady and a chance to contribute.

“I mean, people still listen to (former first lady) Barbara Bush,” she quipped about her mother-in-law. “I certainly do.”