(NEW YORK) -- As a deadly Hamas attack on Israel unfolded last Saturday, Nadav Padan, a reserve general in the Israeli military who lives in New York, received a flood of messages from soldiers he knew in Israel, he said.
Within hours, Padan decided to join the fight. But before he could leave the next day, his teenage son had a slew of questions, Nadav said.
"What's going on in Israel and what are you going to do there? Is it really important for you to fly there?" Padan, now in Israel, recounted his son saying. "Are you going to be at risk?"
The inquiries touched on what Padan called his top worry: "Who will give a shoulder to my wife and son when I'm not there?"
After war broke out last week, Israel called up 360,000 army reservists, which amounts to roughly 4% of the nation's population. Some of those reservists are Israelis who live in the U.S., and they answered the call within days, leaving behind their families.
The departures left family members with tasks like canceling appointments and watering a loved one's plants, they said.
The abrupt change also elicited a mix of emotions: concern for the safety of loved ones and pride in their choice to serve, according to interviews with a current and former member of the Israeli military, as well as a family member of an Israeli soldier.
"I had lots of concerns," Naomi Arbel, who lives in Boston, Massachusetts, said of the moment her husband told her that he planned to join the fight. "But I put aside all my worries because it's not about me. It's about joining our people and defending our country."
Arbel, whose four daughters also serve in the Israeli military, said she has been alone every day since her husband left last week. "Thank god for smartphones and WhatsApp," she said.
The militant group Hamas launched an unprecedented attack last week that has left at least 1,400 people dead and 3,400 people injured in Israel.
In Gaza, 3,785 people have been killed and another 12,500 were injured, according to the Palestinian Ministry of Health.
One Israeli army veteran in the U.S., who spoke to ABC News, said he opposes reservists in the region joining the war.
Elik Elhanan, who served in the Israeli army in the 1990s, refused to join fighting in protest when he was called up in 2002. Since then, he has criticized the Israeli military, which he considers an occupying force that oppresses Palestinians and impedes a peace agreement.
"The best support families can give to those members going to the fight, to the extent it's possible, is to tell them not to go," said Elhanan, who now lives in New York.
"People are hurt and they're mourning, and they want to feel a part of something and somehow heal," Elhanan said. "It doesn't matter how many reservists we send to Gaza -- that is not where hands are needed."
Still, Elhanan, who said his sister was killed in a Hamas attack about 15 years ago, expressed understanding for family members of Palestinians and Israelis involved in the war, especially loved ones of those who may not come home.
"My heart goes out to all the families," Elhanan said.
Padan and Arbel, by contrast, expressed pride in soldiers joining the Israeli military response to the Hamas attack. On Thursday, Israeli soldiers stood ready for an incursion into Gaza aimed at destroying Hamas and ending the terror threat it poses, Israeli officials said.
In response to the questions from his son before his departure, Padan offered a direct response about his reason for joining the fight, he said. "I have responsibility for the future of Israel, and everyone that can help right now should be there," Padan recounted telling his son.
Padan said his choice may bring added stress for his son, who he said worries during hours when military duty requires Padan to be unreachable by cellphone.
Further, Padan and Arbel acknowledged the concerns faced by Palestinian and Muslim families in the U.S. who fear an increase in hate crimes against them.
"Families don't want this," Arbel said. "We all want to live in peace and do our day-to-day stuff."
ABC News' Zohreen Shah contributed to this report.