Israel's Mossad carried out operations "in the heart of Iran" to cripple the country's nuclear program, according to former Mossad chief Yossi Cohen.

Cohen made the statement in during a speech at a World Zionist Organization event in Basel, Switzerland, on Monday. He stated that Iran had repeatedly lied to the U.N.'s International Atomic Energy Agency about its nuclear program, and Mossad operations played a key role in unmasking the regime.

"The Iranian regime is lying to the whole world, and we proved it when we brought thousands of documents from the Iranian archives, documents that proved that the Iranians lied to the IAEA," Cohen said.

Cohen is referring to a dramatic 2018 operation that saw Israeli operatives remove a trove of nuclear documents from Iran's capital of Tehran, including draft designs for a nuclear warhead.

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Yossi Cohen, former head of Mossad and former Prime Minister Benjamin Netanyahu sit together

Prime Minister Benjamin Netanyahu and Yossi Cohen at the Israeli foreign ministry on Oct. 15, 2015. (Gali Tibbon/AFP via Getty Images)

Israel intended the trove of documents to be the final nail in the coffin for the Iran nuclear deal between the U.S. and Iran, which former President Donald Trump had withdrawn from.

President Joe Biden is pushing for a return to the deal, however, leaving many Israeli officials dumbfounded.

"This is madness," former Israeli Prime Minister Benjamin Netanyahu said last week. "This is the height of folly. This should not be done."

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"What will happen is that other countries in the Middle East will pursue nuclear weapons of their own," Netanyahu warned on "Fox & Friends." "So this deal, which is supposed to stop nuclear weapon in the Middle East and the proliferation of weapons of mass death in this neighborhood and beyond, it will actually cause the proliferation of nuclear weapons, and the Middle East will be crisscrossed by nuclear tripwires. It will make the Middle East a powder keg, a nuclear powder keg."

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Israeli officials have warned that Israel will not be a party to any agreement with Iran, and will continue to do "everything" it can to hamper the regime's nuclear program.