In cafeterias across the country, young men speculate about being sent abroad, even though United States officials have said repeatedly that they did not want a war with Iran, and that reinstating a military draft would require congressional approval. At this point, registering for the Selective Service has little bearing on the likelihood of being conscripted.

When Molly Patterson picked up her 17-year-old daughter from school in a suburb of Detroit on Friday, she was stunned when her daughter immediately asked whether her boyfriend would be drafted. The next morning, Ms. Patterson discovered that her 14-year-old son had been up until 3 a.m.; he was feeling stressed after reading about the possibility of war and texting his uncle about whether he could be sent to fight.

Ms. Patterson had not even thought of the possibility of a draft, but her daughter that said it was all that people at school were talking about, and that many were getting alerts on their phones with updates about the airstrike, more than 6,000 miles away. On Saturday, Ms. Patterson found herself trying to quell her children’s fears.