The United States is reportedly pressuring Israel to stop assassinating Iranian nuclear scientists, a number of whom have been mysteriously killed in a campaign thought to be carried out by Mossad.According to CBS News, Obama administration officials have communicated to Israeli intelligence their wish for a cessation of the targeting of scientists in order to allow diplomatic negotiations aimed at rolling back Iran’s nuclear program to take their course.While Israel has never officially acknowledged that it was behind the killings, it is widely believed that Mossad agents carried out the hits in an effort to slow down Iran’s nuclear development as well as to deter the country’s top scientific minds from cooperating with the government’s clandestine weapons program.The CBS News report was written by Dan Raviv, a journalist who along with The Post intelligence correspondent Yossi Melman wrote a book about the history of Israel’s intelligence services.Last year, Melman and Raviv co-wrote Spies Against Armageddon: Inside Israel’s Secret Wars. The book claims that it was Mossad agents, not foreign mercenaries, who took part in the assassinations of four Iranian nuclear scientists. A new, updated version of the book is due out on Sunday.According to CBS News, some in the Israeli intelligence community also had second thoughts about continuing the campaign since they did not want to run the risk of the Mossad’s best spies getting caught.According to Raviv’s chapters in the book, in its pursuit to delay Iran’s military nuclear program, Israeli intelligence services are working with ethnic minorities in or around Iran, such as Kurds and Baluchis, as well as the Iranian Mujihadeen-e Khalq (MEK) organization, which is dedicated to the overthrow of the current Iranian regime. “There is undoubtedly cooperation,” Melman said. The MEK’s 2002 announcement of an Iranian heavy water reactor at Arak and a uranium enrichment facility at Natanz came directly from Israeli intelligence, he added.“They work together. But in the most sensitive missions, it has to be Israeli agents,” Melman said based on what Raviv wrote.Yaakov Lappin contributed to this report.