The head of the Mossad warned Sunday that as the Islamic State terrorist group is beaten back, Iran and its proxies are rushing in to take over its territory.

“The areas where Daesh [an Arabic term for IS] presence is decreasing, Iran is working to fill the void,” Mossad chief Yossi Cohen said during a security briefing to cabinet ministers on Sunday.

In late 2014, the terrorist group controlled approximately 100,000 square kilometers (38,610 square miles) of territory in western Iraq and eastern Syria, according to the US-based RAND Corporation think tank. (The group also controlled an additional 10,000 square kilometers in Nigeria, Libya, Afghanistan and Egypt.) It started losing ground in 2015 and currently controls less than half that area, or some 36,200 square kilometers (14,000 square miles), according to the IHS Conflict Monitor intelligence think tank.

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Israeli security officials have warned that Tehran may use the area of western Iraq and eastern Syria as a “land bridge” connecting the Islamic Republic to Lebanon, through which it can move fighters and weaponry.

Cohen said Iran is also taking over territory for itself and its proxies in Lebanon and Yemen.

The Mossad chief noted that in the two years since the signing of the Iran nuclear deal, known formally as the Joint Comprehensive Plan of Action, Tehran has not abandoned its desire to develop nuclear weapons, and that the agreement “only reinforced that trend and strengthened Iranian aggression in the region.”

The JCPOA came under considerable criticism in Israel for its failure to address Iran’s disruptive non-nuclear activities, and for what Israeli officials described as legitimizing the regime in Tehran and its activities in the region.

During his presentation to the ministers, Cohen said Iran was now enjoying economic growth and international contracts in the deal’s wake.

Prime Minister Benjamin Netanyahu responded to Cohen’s presentation by noting “that Israel is in no way beholden to international treaties signed by Iran,” the Prime Minister’s Office said in a statement.

The Prime Minister’s Office added that “Israel will continue to operate with determination and in a variety of ways in order to protect itself from those threats.”