The shock of Tuesday night’s attack in Libya is reverberating through the tightknit community of Foreign Service families, all of whom are trained to anticipate the worst but also are steeped in the belief that their work is worth the risk.

There are hundreds of families, many based in Washington, in which one parent is on what’s called an unaccompanied tour. That means he or she has been dispatched to a volatile country — too volatile for the State Department to allow the officer to take along a spouse and children.

Sean Smith was in one such family. He was a Foreign Service information management officer killed alongside Ambassador J. Christopher Stevens and two other Americans in the attack on the U.S. Consulate in Benghazi, Libya.

Smith, based in The Hague, left behind a wife, a son and a daughter.

He was on what was supposed to be a brief tour in Libya, the kind of assignment that’s a no-brainer for a Foreign Service family. Most career officers work at least one longer-term unaccompanied tour, and Smith was apparently a veteran of many tough assignments.

Secretary of State Hillary Rodham Clinton on Wednesday offered a tribute to Smith as “a husband to his wife, Heather, with whom I spoke this morning. He was a father to two young children, Samantha and Nathan. They will grow up being proud of the service their father gave to our country.”

Smith was also known as an avid gamer, and tributes from his online friends poured out on social media networks. One wrote on Twitter, “Sean Smith had it right: Use diplomacy in real life and only fight wars with other gamers online. Rest In Peace.”

Such a death is the nightmare scenario for any family, and an especially tangible nightmare for Foreign Service families that live with the daily anxiety that political tensions might turn violent.

Claudia D’Andrea still gets emotional thinking about how she, too, might have been on the receiving end of a call from Clinton.

Two years ago, her husband, Ted, was stationed in Kabul and she remained in Washington with their three young children. After one particularly harrowing incident, “a lot of friends and family were saying, ‘OK, that is enough! Tell Ted he needs to come home now.’ But Ted did not want to curtail which would negate the first seven months and all he had been through so far,” D’Andrea wrote me from Ecuador, where her family is living.

“And, I was managing all right at that point. He made it clear to me that if at any time I could no longer handle it and wanted him to curtail, he would do it. But once I got through that first six weeks, I felt like I could deal with it. So, we held on.”

Through that experience, and another dire one that involved her husband relocating under fire, she said: “I was grateful for the support from friends, in particular. It helped to know that they were worrying about him.

“The kids got that my neighbors were giving me hugs and that there were grim smiles. I hid the front page of The Post from them. When my daughter asked what was going on, I told her that daddy got to have a sleepover. I feel so lucky that this only happened a handful of times. I cannot imagine how hard it must be for [military] families.”

Amanda Fernandez, too, felt a jolt at the news from Libya. Her husband, the father of their two children, has just returned from a year in Afghanistan. They are now “safely reunited” in Washington, she wrote in an e-mail.

“You don’t hear about State Department experiences much because they are not authorized to speak about it on the record and with the media,” she wrote.

She said her husband was motivated to join the Foreign Service because his father had served in it in Vietnam and often spoke of how important the work had been.

“His experience in Afghanistan was the same,” she said of her husband. “We had both been in war zones before (Sarajevo), so this wasn’t new for him, but Afghanistan was different. He was embedded with the military and working at a high level on the peace process. The work sounded really interesting and meaningful.”

For the relatives of those killed Tuesday, Fernandez said, “I can only hope the families’ pain is eventually assuaged by the certainty that their sons, husbands and dads made the ultimate sacrifice doing what they were so strongly committed to and loved.”

The State Department has support networks online and in person for families with a parent abroad. It also has an office devoted to working with families, including a person assigned specifically to families enduring unaccompanied tours, and provides guidance for helping children through the experience.

On Wednesday, a State Department official said the office had been overwhelmed after the attacks. When asked about reaction from Foreign Service families, the official, who asked that she not be named, choked up.

D’Andrea said that it was support from other Foreign Service families, especially those who had been through tours and understood the emotional roller coaster, that she found essential.

For her 3-year-old, it was more difficult, she said.

“A few weeks before Ted was due back, he said, ‘I just want Daddy home for good!” she said, “and I was luckily able to tell him that he would be.”

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