"The moment you see a threat from the sea, you've got something like one minute to deal with it and to finish it, and that's it."
Matan, who did not give his full name, is in charge of an Israeli Navy patrol boat, and he's guarding one of the borders his country is most concerned about: the waters where Egypt's Sinai Peninsula meets Israel.
Two different worlds collide in the Sinai.
The southern part of the peninsula is famous for its resorts. Sharm el-Sheikh and Dahab boast world-class scuba diving and luxury hotels along the Red Sea and the Gulf of Aqaba.
Northern Sinai is the polar opposite: a hotbed for ISIS-linked militants waging a guerrilla-style war against an Egyptian military that has, so far, been unable to suppress the insurgency.
A crossroads between Asia and Africa, Sinai shares a 125-mile border fence with Israel.
Day and night, Israeli security patrols drive along the military road on the Sinai border. The fence stands 15 feet high in places, and listening posts dot the frontier.
The first impression is of a deep and penetrating silence. The Sinai border is not known for disturbances, and the vast emptiness of the Sinai and Negev deserts is overwhelming.
But smugglers have taken advantage of this quiet, attempting to move drugs and humans across the border, according to the Israel Defense Forces.
Until recently, Israel's biggest concern emanating from Sinai was a growing flow of African migrants making their way north, mostly from Eritrea and Sudan.
These migrants sought asylum. The number of migrants peaked in 2011, when 17,300 migrants entered the country, according to the Ministry of the Interior.
In response, Israel built a border fence stretching the entire length of the frontier between the peninsula and the Negev desert in southern Israel.
The border fence virtually ended the flow of migrants. Only 44 crossed into Israel in 2014. But in place of migrants came two different threats: smuggling and terrorism.
As Egypt has destroyed smuggling tunnels between Gaza and Sinai, the smuggling market has moved further south, trying to penetrate the border through Israel.
"They're trying to evolve, obviously," says IDF Lt. Amit Colton of the smugglers. "Therefore, it's becoming more violent drug-smuggling. A more violent border."
"The money is still there, so they are trying to find ways around these physical barriers," says Daniel Nisman, a security analyst with the Levantine Group.
If smuggling is the immediate threat, terrorism is the more serious concern.
Bedouin in Sinai describe ISIS in Sinai as a "cocktail" of some Bedouins, Egyptians from the Nile Valley, Palestinians from Gaza, and other foreigners. The various groups working together have gained a foothold in northern Sinai, and Egypt has not been able to dislodge them.
Militants in Sinai have not carried out any major cross-border attacks, but in early July, they launched two short-range Grad rockets into southern Israel. The rockets landed in open fields, with no reports of damage or injuries. The border has remained relatively quiet, but Israel is aware of the ongoing presence of ISIS Sinai.
"It's loud quiet. There's always stuff going on," says Lt. Colton, stationed along the border. "Unfortunately, we can't see everything. That's a big problem, so we have to be ready to face anything. There is a terrorist threat in Sinai."
On the water, Capt. Matan echoes his concerns: "Today, ISIS is our biggest threat, so we're doing drills like that once a week, sometimes twice, sometimes in the day, sometimes in the night, to make all soldiers ready for everything to come."