Iran continues to be Israel’s primary and most significant challenge despite, even because of, the nuclear deal it signed with the world powers, new Mossad head Yossi Cohen said on Wednesday.Cohen’s comments came at a ceremony, attended by Prime Minister Benjamin Netanyahu, marking his first day in his post. He took over from Tamir Pardo, who served as Mossad chief for the last five years and also attended the ceremony.“Israel is located at the center of the earthquake that has hit the Middle East in recent years,” Cohen said. “Fundamentalist Islamic extremism is washing over states, and leading to their collapse.”Cohen said that the internal religious battles within Islam, as well as the strengthening of the terrorist organizations, makes it incumbent upon the Mossad to understand those threats and thwart them, and to contribute to Israeli security “discretely and with creativity.”Iran continues to call for Israel’s destruction, he said.“It is improving its military capabilities and deepening its hold in our region. Terrorist proxies are a means to further those aims.”The Mossad under Pardo – according to a statement put out by the Prime Minister’s Office – focused on thwarting Iran’s nuclear capabilities, preventing terrorist attacks and the development of terrorist infrastructure around the world, fighting the smuggling of weapons to terrorist organizations, and developing and promoting ties with states with which Israel does not have diplomatic ties. Netanyahu said Israel is facing more challenges than any other country in the world, and is a “bastion of democracy in the heart of a neighborhood full of threats.“The first imperative to ensuring the survival of any living thing, is to identify dangers in time, and beat them back,” he said, adding that he approved the “great majority” of the operations that Pardo bought for his approval.Pardo, who marked the end of some three decades in the Mossad, characterized it as an organization where no mission is impossible, and where there is no problem without a solution. There are good reasons why dozens of intelligence organizations around the world want to cooperate with the Mossad, he said.Cohen, who for the last three years served as Netanyahu’s national security adviser, is also a 30-year veteran of the Mossad who rose through the ranks and held a wide variety of positions, including as director of the department responsible for running agents around the world.On Wednesday, Netanyahu announced that Yaakov Nagel will serve in the interim as Cohen’s replacement as head of the National Security Council, until a permanent replacement can be found. Nagel is currently deputy director for defense and strategic policy in the NSC.