Is Obama's Red Line a Green Light? The use of chemical weapons by Syrian President Bashar al-Assad's regime was finally blown open last week. In a letter to U.S. lawmakers, the White House stated that U.S. intelligence agencies believed "with varying degrees of confidence" that Syria had used the nerve agent sarin on a "small scale." The letter followed others sent to U.N. Secretary General Ban Ki-moon by Britain and France alleging the use of chemical weapons in Syria, and similar assessments by Israeli military intelligence in the last few weeks. Still, President Barack Obama's administration sounded a cautious note. Asked whether Assad crossed the "red line" Obama drew last year that could spur American intervention, a U.S. official replied, "we're not there yet." The White House continues to contend that the evidence is not "airtight," and that it needs further corroboration. In meeting with King Abdullah of Jordan on Friday, Obama stated that "there are a range of questions around how, when, where these weapons may have been used." While these are important questions, especially a decade after the intelligence failure in Iraq, the evidence already gathered by Western countries from inside Syria provides significant evidence of chemical-weapons use by the Assad regime. Here is what I have learned about the regime's use -- and logic for the use -- of chemical weapons over the past six months. The Assad regime's scientists have been experimenting for more than a year with mixtures of toxic and poisonous gasses that could be used to "cleanse areas" of what it calls "terrorists" -- the rebel forces it is fighting. Its security and military apparatus has sought to devise methods to use artillery shells or aircraft to deliver chemical weapons in "localized ways" -- in areas of one or one and a half square kilometers. The regime's logic was that the relentless bombardment of rebel-controlled areas, including in the neighborhoods around the main cities of Aleppo, Homs, and Damascus, had forced most civilians to leave. Civilian casualties, in this warped thinking, could therefore be kept to a minimum if chemical weapons were used in these areas. This was important if the regime was to avoid the attention of the international community, especially the United States, which clearly did not want to intervene in Syria. I first heard this frightening information in the late summer and fall of last year. It came from a small number of privileged Syrians who often travelled to and from Damascus. I had gotten to know and trust them, especially as their information was often corroborated later by other sources and events. All spoke often to current and former senior security officers and regime personalities from the Assad regime's feared security forces, including the presidential guard, Syrian military intelligence, and Syrian air force intelligence -- people they had known in some cases since childhood. Listening to them, it was clear to me that the regime had the intention to use these horrendous weapons -- and that it would do so as it came under further pressure in key strategic areas, especially the major cities in the west of the country. According to my interlocutors, Assad and those closest to him had been emboldened by the international community's weak response to his bloody military campaign. The United Nations claimed in February that the death toll from the fighting in Syria was well over 70,000 people, while, during that same month, a lieutenant from Syrian military intelligence informed one of my Syrian interlocutors that the regime estimated that around 85,000 civilians had been killed, with many more thousands "missing." Successive statements from Obama and senior U.S. officials, these interlocutors said, had been interpreted by the regime as a "green light" to continue its campaign. The exclusive focus on political and diplomatic solutions, as well as the international community's rising fear of Islamic jihadists, further reinforced the regime's belief that "the U.S. and its Western allies did not mind the current military operations," according to a retired general in Damascus. Like any war, there are political and diplomatic efforts, while it is the winner that dictates terms in the end. In the eyes of the regime, therefore, Obama's "red line" prohibiting the use of chemical weapons -- first drawn last August, in the midst of an election campaign -- had to be tested. By December, it was becoming clear that the regime had started to use these weapons. One attack was recorded on Dec. 23 in a suburb of Homs -- a retired Syrian general had told one of my Damascene interlocutors very soon after that the regime was now "using some kind of formula or gas" as a "preventive weapon." In Homs specifically, it had used a "light sarin combination." According to a major in the Presidential Guard, officers were now carrying protective gas masks. This is also when senior Western officials started murmuring of the possible use of chemical weapons by the Assad regime. The regime was heartened by the feckless international response in the aftermath of the Homs attack. It noted the careful response of Tommy Vietor, then a U.S. National Security Council spokesman, who said reports of the Homs attack were "not consistent with what we believe to be true about the Syrian chemical weapons program." Vietor was refuting the view expressed by U.S. diplomats in a leaked cable from Turkey that stated there was a "compelling case" regime forces had used poisonous gasses in Homs. It was also comforted by Joint Chiefs of Staff chairman Martin Dempsey's admission in January that "the act of preventing the use of chemical weapons would be almost unachievable." Over the past few months, the regime has continued to test Obama's red line. It has continued to use sarin, possibly with other mixtures of poisonous gasses and chemical agents, in small doses. Furthermore, it has also been moving these chemical weapons, especially as it came under pressure from rebel forces. According to one of my Damascene contacts, a senior officer in Air Force Intelligence recently admitted that the regime has used these chemical weapons in March in the Damascus suburbs of al-Otaiba and Daraya, and in the Aleppo suburb of Khan al-Assal. Ominously, the same officer said that while the regime had not used other chemical weapons in its possession, such as anthrax and VX nerve gas, it would "use these without hesitation" if it felt the need to do so. Another senior regime security official relayed to another interlocutor that "when the time comes, and the regime feels that Damascus is falling, we will use all kinds of weapons and means to keep it." Now that events -- not to mention the protestations of Britain and France -- have forced Obama's hand, is this really a "game changing" moment? The simple answer is that it should be. As the administration seeks to buy time, it would do well to remember that Assad and his cabal -- as well as his backers in Tehran, Lebanon, and Iraq -- will be watching the United States' resolve on this issue closely. This is probably Obama's last chance to have a decisive impact on the downward spiral toward chaos in Syria and the broader region -- a situation which one senior U.S. official recently described to me as "one giant Florida sink hole." So what should be done? My colleague Bruce Riedel gets it right when he argues that Obama needs to go to the United Nations, in much the same way that Bush senior (certainly not junior) did in isolating Iraqi dictator Saddam Hussein after his invasion of Kuwait in 1990. This is an opportunity to establish Assad and his regime as the international pariahs that they undoubtedly should be. In this regard, a first step should be to demand that the U.N. inspection team established last month be allowed to enter Syria immediately, and report quickly on what it finds there. There will be inevitable comparisons to the run-up to the Iraq war, but Syria is different. A U.N. inspection team is already in place, and was ironically requested by the Assad regime after what was a botched chemical weapons attack in Aleppo in March. It is currently in Cyprus, ready to go, but Assad has so far blocked its entry into the country, insisting that the investigation be limited to the Khan al-Assal attack. In striking contrast to Iraq, this time the evidence is already there to be examined and the reality is that there is no looming unilateral U.S. military action. If the U.N. route is to work, however, the United States and its allies must not allow the Assad regime to delay any longer. If necessary, they must bring a new resolution to the U.N. Security Council demanding that the inspection team enter -- and ask China and Russia some very difficult questions if they wish to delay this further. There will, of course, be continued uncertainty as to whether Russia will continue to block U.N. action. But it is possible this latest incident could cause Moscow to change its tune: In early December, Foreign Minister Sergei Lavrov warned his counterpart, Walid Muallem, against the use of chemical weapons. According to a Damascus-based source in contact with senior regime figures, Lavrov supposedly said that the use of such weapons "will put Russia in an awkward position," and hinted that it would not be able to support them internationally. The regime's criminal use of such weapons has now put Moscow in such a position. There is, of course, no guarantee that diplomatic efforts at the United Nations can stop Assad from using chemical weapons, let alone end the daily killing of civilians inside Syria. As many Syrians now know, this regime has proved again and again that it will stop at nothing to stay in power. U.S. diplomacy should therefore also be focused on gaining international support for the credible threat of the use of force if the Assad regime continues to flout international law. The inability to protect civilians in Syria has been one of the biggest failures of the international community in recent times. The use of paramilitary death squads, which have committed massacres of civilians; the shelling of civilian areas; the use of helicopters and regime aircraft to bomb entire neighborhoods, including bread lines and bakeries; and the use of over 200 Scud missiles should all have been red lines for the international community in Syria. That these previous outrages have not spurred international action has only encouraged Assad to use increasingly brutal measures against his people. In my latest discussion with a visitor from Damascus, I heard this chilling statement relayed from a senior regime figure: "The regime is revenging from the people. They have ruined the country; they have ruined themselves. They have ruined us. It's time for the world to act before the Assad regime adopts even more brutal ways to massacre its own people. The continued use of chemical weapons in Syria demands the establishment of a no-fly zone and humanitarian safe zones, to protect Syrians who may have nowhere else to go and who face an increasingly beleaguered and vengeful Assad regime. As in the cases of Rwanda, Bosnia, and other sorry episodes of international procrastination, history will not judge well those who counsel inaction. When war crimes and crimes against humanity are being committed inside Syria, it is time for the international community -- particularly those who are in a position to lead it -- to make good on its red lines. Purposeful diplomacy, backed by the intention to use force if necessary, may be the only way to make Assad understand that international law and basic human values are no longer negotiable in Syria. These efforts should support the development of an inclusive national compact that reassures and unites all Syrians. Obama and the United States must now lead a decisive and relentless international effort to protect Syrians from their own regime.