President Barack Obama has announced that he will seek authorisation from Congress during the week commencing September 9, for a limited missile strike against the Assad regime. This follows the release on August 30 of a US intelligence report, which concludes with “high confidence”, based on intercepted communications, overhead surveillance, video and witness statements that the regime carried out a substantial chemical gas attack near Damascus on August 21. The US intelligence study, which counterparts recent French and UK government reports, concludes that the chemical attack killed at least 1,429 Syrians, 426 of them children. US Secretary of State John Kerry described the conclusions “as clear as they are compelling…[but] I’m not asking you to take my word for it. Read it for yourself, everyone, those listening, all of you, read for yourself the evidence from thousands of sources, evidence that is already publicly available.” The framework of international debate in recent days has centred around the 1925 international convention about chemical warfare and the practice of intervention by foreign countries for humanitarian purposes. From this perspective, an international response is necessary to uphold prohibition of chemical weapons use after the horrors of World War I. UK Prime Minister David Cameron described the Syrian use of chemical weapons as the “most abhorrent use of chemical weapons in a century” and called upon the international community to “uphold the international taboo of chemical weapons.” Meanwhile, Kerry asserted that this issue “matters to [US] security and the security of our allies. It matters to Israel. It matters to our close friends Jordan, Turkey and Lebanon, all of whom live just a stiff breeze away.” The depth of intelligence and information on the chemical attacks that have been released underlines a stark contrast with the 1920s when, for instance, there were no satellites and modern communications. There is also a clear contrast in the intelligence evidence that has been assembled compared to that about Iraq a decade ago. Chemical warfare was one of the heinous methods deployed by Saddam Hussein. There was plenty of evidence for it in his attack on the Kurds, but it was not so clear whether he was planning to use those weapons in 2003. There was, however, enough suspicion that the United States and United Kingdom intervened militarily. Scientists were particularly doubtful at that time about the estimates of the range over which Iraqi weapons could endanger other countries and about how rapidly they could be deployed. Unfortunately, no UK or US scientific review was produced before, during or after that conflict, but the forthcoming UK Chilcot report may have some evidence of that sort. Unlike in previous conflicts, much information and evidence is now available in near real time. For example, complex chemicals can now be detected though satellite measurements in the urban areas where conflict is taking place, and the gases that enable these chemicals to be dispersed can also be computed. In general, people are much less suspicious of data in real time. And we must now have much more open scientific data, and this requires government scientists to consider how we can distribute more information. But we must go even beyond this. That is, to build more international confidence in the information, in this post-Iraq era, it must increasingly be produced by countries beyond the United States and United Kingdom too. Much work is going, right now, in European laboratories and space and environmental companies. And, if more of this information were made available, particularly in collaboration with countries like Iran, Russia and China, which all have these instruments and can make these measurements, it would be possible through much wider distribution of information for many more people right across the world to see and understand this. It is particularly important to enable people on both sides in Syria, and in the wider Middle East too, to have more information about what has happened, including the possibility of tracking and communicating any future illegal use of weapons in conflict zones. This will surely build confidence, make more likely collaboration with, and support from, other countries, and help support other organisations in their crucial humanitarian efforts. The writer is a Visiting Professor at Delft University and former Director-General of the UK Met Office