Hamas continues to play a double game when it comes to the Islamic State. The Palestinian terrorist organization is trying to supress ISIS-inspired jihadists in Gaza, while simultaneously cooperating with the terrorist group's Sinai Peninsula affiliate – Wilayat Sinai.

Despite some tactical benefits, Hamas' seemingly counterintuitive, yet calculated, engagement with Islamic State elements has resulted in tangible setbacks for the Palestinian group. Palestinian sources speaking with the Times of Israel revealed that dozens of Hamas operatives have defected to Wilayat Sinai, including highly trained terrorists from elite units.

Roughly two months ago, Hamas forces arrested Abed al-Wahad Abu Aadara, a Hamas naval commando who defected to ISIS after he re-entered Gaza. His brother also joined ISIS and died in clashes with the Egyptian military. Facing pressure from ISIS, Hamas recently released Abu Aadara from prison.

Other defectors include highly trained Hamas operatives who enhance the Islamic State's ability to build bombs and use anti-tank missiles. Senior military wing members, including Abu Malek Abu Shwiesh, a key assistant to Hamas' Rafah commander, reportedly joined Wilayat Sinai.

The ISIS affiliate has created significant Egyptian casualties in recent years, particularly after acquiring and deploying sophisticated weaponry in the Sinai.

Israeli officials have outlined detailed aspects of Hamas-Islamic State cooperation in the past. Both organizations engage in smuggling terrorists and arms, including advanced weapons systems. For example, Hamas provided Wilayat Sinai with Kornet anti-tank missiles that have destroyed Egyptian military vehicles. Hamas also provides military training and medical services for injured Wilayat Sinai fighters in Gaza, in addition to reportedly transferring money directly to the terrorist organization.

In return, Hamas cultivates a safe haven for its leaders and fighters in case of a future confrontation with Israel, understanding that Israel's military engagement on Egyptian territory is limited.

Since the end of the 2014 summer war in Gaza, Hamas has invested significant resources into reconstructing its terrorist infrastructure. It also continues to rebuild its elite forces – including its naval commando unit – dedicated to infiltrating into Israel to carry out terrorist attacks. Reports of Hamas defections are a clear setback for the Palestinian organization, but are not likely lead to a wider rift with the Islamic State.

Despite broader ideological differences, both groups remain committed to challenging the Egyptian military in Sinai and destroying the Jewish state.