Israel’s security agency said Friday that two Arab-Israeli brothers had been arrested for allegedly planning to travel to Syria to join the Daesh extremist group.

Israeli police and the Shin Bet arrested 20-year-old Na'im 'Abd al-Karim Qassem Jabarin and 25-year-old Mahmoud 'Abd al-Karim Qassem Jabarin in the town of Umm el-Fahm, and a raid of their home revealed a Carl Gustav recoilless rifle on the roof along with Daesh paraphernalia.

The brothers were arrested in July, but a gag order kept details of the case from being made public until Friday according to Jerusalem Post.

The authorities also seized photographs that “reinforced suspicions that the two supported the ideas and ideology of [Daesh]," according to a Shin Bet statement.

Authorities received intelligence indicating that Mahmoud had been in contact with a former Umm el-Fahm resident who has been based in Syria since 2014 and is known to be a Daesh recruiter. The information suggested that the recruiter was going to help Mahmoud travel to Syria from Israel to join the extremists.

Investigators also found that Naim had "sworn fealty to the head of [Daesh], Abu Bakr al-Baghdadi, and considered himself an operative of the… organization," the Times of Israel reports.

The Haifa district attorney charged Naim with possession of illegal weapons while Mahmoud was indicted for collaborating with a foreign agent.

The arrests come not long after three Arab-Israelis from Umm el-Fahm shot and killed two policemen guarding the Al-Aqsa mosque in East Jerusalem on July 14 before being killed themselves, prompting Israel to temporarily install security cameras and metal detectors in the area.

Fadil Tzaber Kna'anah, a 25-year-old resident of Nazareth, was arrested in March for allegedly transferring money to two Arab-Israeli Daesh militants.

Shin Bet wrote in Friday’s statement that it "views Israelis who support [Daesh] as a serious security threat, especially those who are in contact with organization operatives and desire to fight in its ranks."

"As such, the Shin Bet will continue to monitor suspects and take the necessary enforcement measures to prevent the dissemination of [Daesh] ideology in Israel and prevent Israelis from fighting with the organization."

Although several Arab-Israelis have been arrested on suspicion of having connection to Daesh and attacks planned by the jihadist group, Israel itself has not experienced an attack by those particular extremists.

Some 50 Israeli citizens have traveled to Syria to fight with Daesh and other rebel groups, according to Shin Bet. In November 2016, several Arab-Israelis were also arrested and jailed for trying to join Daesh in Syria, with another Arab-Israeli actually using a hang glider to float over the Israeli-Syrian border.