Mitt Romney's eyes filled with tears Monday as the Republican presidential contender recalled watching the casket of a soldier killed in Iraq return to the United States and imagined if it were one of his five sons.

Adding a poignant twist to a story he often tells on the campaign, Romney recalled the scene at Boston's Logan International Airport while he was Massachusetts governor to make the point that the country remains united despite its differences over the war or other national challenges.

It was a counterbalance to a moment earlier this year, when Romney told a woman in Iowa that his grown sons — none of whom has served in the military — were serving the country by helping with his campaign. Romney later apologized for the remark, saying it was wrong to equate military service with campaign involvement.

"The soldiers that I was with stood at attention and saluted," Romney told employees at Insight Technology Inc., a company that makes infrared optical equipment for U.S. troops. "And I put my hand on my heart, and tears begin to well in your eyes, as you can imagine in a circumstance like that. I have five boys of my own. I imagined what it would be like to lose a son in a situation like that."

Eyes misting as he finished the story, Romney recalled glancing up at the massive windows in the U.S. Airways terminal.

"As I looked up there, every single hand was on every heart, and I recognized this is a nation that comes together and respects and reveres those who serve this great nation, and who joins in mourning when one of them is lost."

He added: "This is a nation which is united. Do we face challenges? Absolutely. Do we face a time when we need to change course in some important ways, absolutely? Can we do that as Republicans and Democrats together? We've done it time and again. You see it happen in state after state; it doesn't happen enough in Washington," he said.

During a news conference afterward, Romney defended the tears, which came a day after he similarly choked up on NBC's "Meet the Press." He did so while recalling the relief he felt after the Church of Jesus Christ of Latter-day Saints, the Mormon church of which he is a member, granted full privileges to blacks in 1978.

"I'm a normal person, I have emotions," Romney told reporters. "I have emotion just like anyone else. I'm not ashamed of that at all."

Romney's appearance at Insight veered off course when an attendee asked Romney why a woman — who turned out to be from the anti-war American Friends Service Committee — had been thrown out while distributing cards with a series of questions. The attendee asked if organizers considered such questions "toxic material."

Romney replied, "There is nothing that's toxic to me; I was on 'Meet the Press' yesterday, for Pete's sake." He then grabbed the card and answered a series of questions, which focused on the Iraq war and alternate uses for the money being spent in the battle.