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NITZANA, Israel — As Sgt. Talia Ben Tuvia scanned the Israel-Egypt border, there was no doubt in her mind that ISIS would one day attempt an attack from beyond the frontier.

"We don't see the Daesh fighters, but they are there in [Egypt's] Sinai and are threatening to harm Israel," she said, using another name for the extremist group.

The 21-year-old is one of the female soldiers prepped for battle on Israel's front lines.

Sgt. Talia Ben Tuvia stands at her outpost on May 15. Dave Copeland / NBC News

She serves as a member of the Karakal Battalion, which was founded in 2000 and is the country's first to have male and female soldiers fighting side-by-side. Women form between 60 and 70 percent of Karakal, which gets its name from a species of desert cat whose gender is barely distinguishable.

Before the unit was established women were not able to serve as full combat soldiers in Israel.

"We are prepared against any attack," Ben Tuvia told NBC News during a visit to her base near the border crossing earlier this month. "It may happen today [or] in a year or two but we are prepared and know it will happen … We are strong."

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ISIS has been able to recruit fighters in Egypt by exploiting the political instability that led to President Abdel-Fattah el-Sissi's crackdown on Islamist groups.

With the jihadis' numbers swelling to some 2,000 fighters in the region, some Israeli security experts believe the extremists are contemplating an assault on the frontier guarded by Ben Tuvia and her fellow fighters.

A member of Israeli's Bardalas Battalion during a training session in northern Israel. Dave Copeland / NBC News

"ISIS in Sinai is interested in lunching a dramatic attack along the Israeli border in order to intensify its popularity," said Michael Barak, a senior researcher at the International Institute for Counter Terrorism, a think tank based in the Israeli city of Herzliya.

NBC News took the bouncy ride in an American-made Humvee along part of that boundary, which stretches for 245 miles from the Israeli port of Eilat to Rafah, in the Gaza Strip.

Because Karakal Battalion is the main force protecting the border between Egypt and Israel, it's likely that any ISIS militant attempting the crossing would come face-to-face with one of the women.

"I’m very proud to be a female soldier standing here saying that I’m not scared of ISIS," Ben Tuvia said. "In the end it doesn't matter if I’m a boy or a girl. If I have a gun we can all do the same thing."

Members of Israel's Bardalas Battalion carry out a drill in northern Israel. Dave Copeland / NBC News

One of her male counterparts, Sgt. Rubi Ayash, said it took time to get used to having women on his team, but now he's sold on the idea.

"There are a lot of advantages to mixed battalions — they bring in a new way of looking at things and obviously it’s more interesting," he said.

To join the Karakal Battalion, volunteers must go through two days of mental and physical challenges.

On its website, Israel's army warns prospective female recruits — whom it calls "girls" — that "the course is strenuous and identical to that of any other exclusively-male battalion."

Related: Sex-Change Israeli Army Officer Speaks Out

Since Karakal was established, the army has launched two more mixed battalions.

Sgt. Kineret Hamada of the Bardales Battalion told NBC News she always knew she would be a soldier, just like her father, brothers, uncles and cousins before her.

"It was very important for me to give more for the country," she said. "Many people disrespect combat women soldiers, which can lower your motivation, but I want my girls to hold their heads up and be proud and know they are doing something important."

Asked if she was afraid of facing ISIS, Hamada replied with a smile: "We are waiting for this and are not afraid. This is what we are training for."