US President Barack Obama has ordered his national security team to prepare a declassified report for public release before any military strike in Syria commences, CBS News reported on Monday.Obama made the request at a Saturday White House meeting of his national security team, in which according to CBS, there was a consensus opinion about the need to respond military to alleged chemical weapons use by the regime of Syrian President Bashar Assad last week. CBS reported that the declassified report, presenting what the US believes is an "airtight circumstantial case" that the Assad regime was behind the chemical attack that killed more than one thousand people last week, would be released publicly "in a day or two." A visibly angry Secretary of State John Kerry said on Monday that it was “undeniable” the Assad regime has used chemical weapons on a massive scale, and that Obama would respond strongly.“This is about the large-scale, indiscriminate use of weapons that the civilized world, long ago, decided must never be used at all,” Kerry said.He said that, as a father, “the images of entire families dead in their beds without a drop of blood, or even a visible wound” shook his consciousness and that of the nation.He said an attack of this “staggering scale could not be contrived or fabricated.”“Make no mistake,” Kerry warned, “President Obama believes there must be accountability for those who would use the world’s most heinous weapons against the world’s most vulnerable people. Nothing today is more serious, and nothing is receiving more serious scrutiny.”The United States is preparing legal justification for the use of force against Syria with allies Britain and France that would circumvent the United Nations Security Council, where Russia and China have vowed to block any resolution authorizing military intervention in the conflict.The US will detail its case soon, with military action possibly in the coming days, sources tell The Jerusalem Post.Iran warns against strike on SyriaIran warned on Tuesday against foreign military intervention in Syria, saying the resulting conflict would engulf the region.Iran, which is supporting Assad against rebels seeking to overthrow him, has said rebels were behind the suspected attack, and said on Tuesday the West was using it as a pretext to intervene in Syria."We want to strongly warn against any military attack in Syria. There will definitely be perilous consequences for the region," Iranian Foreign Ministry spokesman Abbas Araqchi told a news conference. "These complications and consequences will not be restricted to Syria. It will engulf the whole region."Shi'ite Iran is Syria's closest ally and has accused an alliance of militant Sunni Islamists, Israel and Western powers of trying to use the conflict to take over the region.As well as backing Assad, Iran also supports the Lebanese Shi'ite group Hezbollah which has sent fighters into Syria to help the government there. Tension is also rising between Hezbollah and Israel over cross-border rocket attacks.Michael Wilner contributed to this report.