Olivier Guitta is the Managing Director of GlobalStrat, a security and geopolitical risk consulting firm for corporations and governments.

In his last address to the United Nations General Assembly, Barack Obama mentioned Syria in passing. It should have been the central theme of his speech but, as Laurent Fabius has said, Obama was never serious about solving the Syrian crisis. While a ceasefire brokered with Russia is theoretically in place, both Syria and its faithful ally, Russia, have been carrying out their deadliest campaign in Aleppo unhampered. Furthermore, America’s passivity on Syria is aiding ISIS and directly threatening directly the homeland.

The laissez-faire policy of Obama – which consists of leaving Syria and Russia to massacre civilians and Turkey to attack the Kurds, who have been the only effective anti-Islamic State force – has enormous consequences.

As Nicolas Sarkozy has noted, action is not Obama’s forte – and in no other place has this proved more true than in Syria. Obama’s first major error took place in 2013, after a chemical attack in Ghouta conducted by Bashar al-Assad forces killed more than 1,400 civilians, including scores of children.  This clearly crossed what Obama had called a “red line”, but was met by a disgraceful silence. Indeed, he refused to take David Cameron’s calls for three days before a planned missile strike against Syria was due to take place. This disdain for his allies was felt even more directly France.  It had fighter jets ready to take off on the tarmac to bomb some of Assad’s key positions, but cancelled the operation when told that it was on its own.

This Western inaction was the ideal propaganda and recruitment tool for the anti-Assad jihadists in Syria, including ISIS. Its rationale for convincing young western Muslims was simple: “Your government is supposedly defending human rights but, when it comes to saving Muslim lives, it doesn’t care: we need your help, come join us.” The message had impact: droves of Western Europeans travelled to Syria to join jihadist groups. So the first struggle that the West lost against ISIS was a consequence of non-intervention against Assad.

The second lost battle occurred when the U.S intervened militarily in Iraq in 2014 against IS. The latter made the case that the U.S had thus sided with the Shias and declared war on the Sunnis. This narrative brought even more recruits to join the IS in Syria and Iraq, and also prepared the way for attacks against Western nations. Some have argued that without the U.S. intervention in Iraq in 2014, following the non-intervention in Syria the year before, ISIS would have not have rushed to target the West.

As the Assad regime continued to massacre its people including by the means of chemical attacks, proof that Obama had long decided to side with Assad kept on springing up. Examples are: the CIA’s suggestion that at least 50 different plans to overthrow Assad that were turned down by Obama; and the refreshing and brutally honest mea culpa by Frederic Hof, a former American diplomat.  Furthermore, Obama’s lenient policy on Iran, including a very advantageous nuclear deal, has been a central point of his administration foreign’s policy, and has reinforced Islamic State’s claim that the U.S. has sided with the Shias. It marks the first time in recent history that the U.S. has taken a side in the 1,400-year-old conflict between Sunni and Shia Islam. This decision has reinforced ISIS’s argument that 90 per cent of the worldwide Muslim population – the Sunnis – is now shunned by the U.S.

Additional proof of Obama’s protection of Assad emerged last week, when the Washington Post revealed that the White House has worked behind scenes to prevent a bipartisan bill to sanction the Syrian regime for war crimes from getting a vote in the House of Representatives. This is a godsend for Islamic State propaganda. It has also helped to create a wave of homegrown jihadists that have already begun attacking American civilians at home. Omar Mateen, the ISIS-linked jihadist that killed 49 people in the worst shooting of U.S. history at the Pulse nightclub in Orlando in June explained his attack this: “You have to tell America to stop bombing Syria and Iraq. They are killing a lot of innocent people”.

In a memo earlier this year, more than 50 American diplomats urged strikes against Assad. Until the U.S. reverts its policy and decide to go hard after him, ISIS will win the hearts and minds of scores of Sunni Muslims in the West  The Obama Administration will be remembered for having sided and de facto saved Assad – a war criminal who is responsible for the deaths of up to 450,000 people.