Dozens of Hamas’ top fighters have defected to the Islamic State’s Sinai-based affiliate in recent years, though cooperation between the two terrorist groups remains strong, Avi Issacharoff reported Wednesday in The Times of Israel.

Palestinian sources told Issacharoff that Abed al-Wahad Abu Aadara, the first known member of Hamas’ naval commando unit to have defected to Sinai Province, was arrested when he returned to the Gaza Strip two months ago. Abu Aadara joined Sinai Province after his brother died fighting for the group.

His arrest precipitated an increase in tensions between Hamas and Sinai Province, including a reduction in goods being smuggled into Gaza. However, after a recent rapprochement between the two groups, particularly related to smuggling, Hamas released Abu Aadara.

“In recent years Hamas has lost dozens of members of its military wing — the Izz ad-Din al-Qassam Brigades — to IS’s Sinai Province, including a number of its fighters from the elite Nukhba unit,” Issacharoff explained. “Many of these operatives left for Sinai with their families and relatives and now serve as the Sinai Province’s main points of contact with Hamas. These defectors include a number of Hamas’s experts on operating anti-tank missiles and assembling roadside bombs, who have provided substantial assistance to IS in its war against the Egyptian army.”

Despite the defections, Hamas “continues to cooperate with the Sinai Province,” especially “in relation to smuggling from Sinai into Gaza.” Hamas leadership in Rafah remains in charge of cooperation with Sinai Province, including in the realms of arms smuggling and medical care for injured fighters.

The close cooperation between Hamas and Sinai Province recalls Israeli Prime Minister Benjamin Netanyahu’s observation before the United Nations General Assembly in September 2014 “that ISIS and Hamas are branches of the same poisonous tree.”

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