Iraqi forces closed in on Tikrit Tuesday, their progress slowed by jihadist snipers and booby traps, on the second day of Baghdad's largest operation yet against the Islamic State group. The government has mobilised a 30,000-strong force for the push to retake Tikrit made up of Shiite militiamen and Sunni tribesmen as well as troops and police. Iraqi forces are moving on Tikrit from three directions, with units targeting the towns of Al-Alam and Ad-Dawr to the north and south, while another large contingent drives on the city from the east. The jihadist group announced in a radio bulletin Tuesday that a US national from its ranks had carried out a suicide attack against Iraqi forces near Samarra, the other main city in Salaheddin province.

By Dan Williams and Matt Spetalnick WASHINGTON (Reuters) - Israeli Prime Minister Benjamin Netanyahu warned U.S. President Barack Obama on Tuesday against accepting a nuclear deal with Iran that would be a "countdown to a potential nuclear nightmare" by a country that "will always be an enemy of America". "If the deal now being negotiated is accepted by Iran, that deal will not prevent Iran from developing nuclear weapons - it will all but guarantee that Iran will get those nuclear weapons - lots of them," the Israeli leader said in a 39-minute speech to the U.S. Congress that offered a point-by-point critique of Obama's Iran diplomacy.