The decision of the US finally to punish Bashar al-Assad for the use of chemical weapons against civilians will turn out to be, no doubt, a catalyst for a new chapter in the Syrian conflict. Even though US officials repeatedly emphasised the missile strikes on the Shayrat airfield were a one-off punitive measure, the unprecedented move comes amid a set of turning points in different parts of Syria and in the way foreign actors operate there. It is against the backdrop of these changes that the regime’s logic behind the use of chemical weapons should be viewed.

Paradoxically, recent changes in the conflict have seemed to favour the regime. Exactly one week before the missile attack, American officials gave Assad something he long wanted, namely, a new stated policy that his removal was no longer a US objective. This came in the form of top-level remarks from Rex Tillerson, the secretary of state, Nikki Haley, the US ambassador to the UN, and Sean Spicer, the White House press secretary, stating that the long-term status of Assad would be decided by the Syrian people .

The message was cause for celebration in Damascus, especially as the about-face reflects the approach of the opposition’s regional and international backers in recent months.

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Turkey, for example, turned its attention wholly to its operation Euphrates Shield campaign to check the expansion of the Kurdish YPG, or the People’s Protection Units, which Ankara considers a terrorist organisation, and to combat Islamic State. Since the campaign began in August, Ankara worked closely with Russia to ensure freedom of operation and several officials frequently stated that the removal of Assad was no longer a Turkish objective. Binali Yildirim, the prime minister, even went so far as to suggest that Ankara would prefer it if the Syrian regime took control of Manbij, a former Isis stronghold liberated by the YPG.

The Gulf states have also reduced their involvement in the Syrian conflict to a minimum. Qatar, the most committed Gulf backer, is less able to increase or even maintain its support, particularly since the Turkish-Russian rapprochement, as aid typically went through Turkey. Saudi Arabia, which continues to support the rebels through the US-run military operations centre in Jordan, has now minimal involvement in military support. The United Arab Emirates, meanwhile, appears to have fully pulled out any support provided to the rebels. Jordan’s army chief, Maj Gen Mahmoud Freihat, told BBC Arabic in December that Amman would open the borders if the regime took control of the Syrian side.

These statements from regional backers of the opposition represent a remarkable win for the regime and a profoundly frustrating psychological and operational blow to the rebels, particularly after they were expelled from eastern Aleppo in December. The regime feels its future is not threatened, even while the insurgency against it persists.

The US, meanwhile, continued to focus on its effort in the fight against Isis and al-Qaida. In recent weeks, this focus on extremists began to pay direct dividends for Assad. Last month, for example, the US helped the regime and its Russian and Iranian allies in their campaign to expel Isis from Palmyra by conducting airstrikes against the group there. Also, the planned US operation to dislodge Isis from Raqqa will rely on the YPG-led Syrian Democratic Forces, which have no qualms about co-operating with Damascus and Moscow, rather than the Turkish-backed rebels who seek the downfall of Assad.

The burning question, then, is why the regime would gamble with all those gains? Those who cast doubt on the culpability of the regime in the chemical attack in Khan Sheikhoun, in the northwestern province of Idlib, argue that the behaviour appears illogical and thus unlikely. The regime has everything to lose and little to gain from such an act. On the other hand, what prompted the US to change its posture towards Assad within exactly one week, from declaring that his survival was none of the US’s business?

One explanation of the regime’s motive offered by analysts, such as Faysal Itani of the Atlantic Council, is that the use of chemical weapons in Idlib was a prelude to Damascus’s effort to recapture this rebel-held province. Idlib, which has the only provincial centre controlled by the rebels, is vital in the regime’s long-term plan to control all of the country. The use of chemical weapons will terrify the local population and weaken the rebel resolve there.

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As Itani explained, the use of chemical weapons is sometimes a tactical necessity for the thinly stretched Syrian army. The regime got away with chemical attacks dozens of times before and it might not have anticipated an American response.

But what if a US response was part of its calculus? I believe this is a possibility, based on previous conversations with regime supporters, and a theory shared by a former senior regime insider.

If Damascus cleared the use of the poison gas in Idlib, it likely anticipated two scenarios: the US would either respond with punitive measures or continue to ignore such attacks. The regime knows that the consequences of the first scenario, while real, are limited. The regime, its backers as well as its opponents, recognise that the US has no interest whatsoever in destabilising it, at least while the threats of Isis and al-Qaida are still present. Contrary to popular narrative, even regional backers of the opposition have no interest in the disorderly fall of the regime.

Here, then, might have been the thinking before the attack: if the US were to opt for inaction, as usual, the regime would obviously stand to benefit from setting the tone against the new administration in Washington. Despite the change of rhetoric in Washington a week before, the situation in Syria was still fluid and the regime believes it had a high point of leverage as the US readies its troops to fight in Raqqa. Rather than showing gratitude to the changed tone, runs this theory, a regime such as the Syrian one would not risk wasting such an opportunity to double down and gain tangible compromises from the US, which can change its policy after Raqqa.

Facebook Twitter Pinterest ‘A message to Russia itself’: Bashar al-Assad with Vladimir Putin at the Kremlin in 2015. Photograph: Alexei Druzhinin/AP

Russia has insisted that it opposes any offensive in Raqqa that does not go through Damascus and Moscow. Unlike previous US-led offensives against Isis, the regime positioned its troops near the front lines in Raqqa, as well as between Raqqa and areas controlled by the Turkish-backed rebels in the eastern countryside of Aleppo. So, in this scenario, the regime viewed that the time was ripe for playing rough with the Americans and the use of chemical weapons would be a tool of defiance.

And what if the US was to respond, as it did? Such a scenario counterintuitively serves a fundamental purpose for the regime, which goes to the heart of specific fears by Damascus and Tehran. Such fears arise from a stated plan by the Trump administration, to drive a wedge between Russia and Iran as a way to roll back Iranian influence in the region.

A US escalation against the regime will, instead, widen the distance between Moscow and Washington. “I don’t rule out the possibility that this was a message from the regime to Russia itself,” the former regime insider said. “They are worried that the Russian policy in Syria does not serve their interests and want to show to the Russians they can be spoilers.”

Russia’s approach in Syria is not in sync with that of Damascus and Tehran, even if they all work for the same goal – the preservation of the regime. Moscow’s outreach to some rebel forces, to Turkey and to the US goes counter to the Iranian-led approach before the Russian intervention in September 2015. At least some Syrian and Iranian circles see risks in the US-Russian understanding in Syria and the potential to force a settlement on them in the future. Instead of separating Russia from Iran, the US action brings them closer and increases the distance between Russia and the US. Russia already announced it was suspending a “deconfliction” agreement with the US to avoid air accidents in Syria

Outsiders may find it strange a regime would put itself at risk, but those who know it from inside understand the logic

It is impossible to verify whether the regime considered such a scenario, but there should be no doubt that Damascus and Tehran are conscious of, and worried about, Team Trump’s plan. Notwithstanding the regime’s thinking, the missile strikes have so far had that effect. Outsiders may find it strange that a regime would put itself in unsavoury risks, but those who know it from the inside understand the logic and the need to ensure it is not exposed to the most real risk to its interests today.

That risk – divergence with Russia – may become more realistic if the US increases its footprint in Syria and if Russia finds it necessary to collaborate with it and regional countries to impose a new reality. For Iran, Washington’s plan affects it in three countries – in Syria and Iraq and Yemen, where the US has substantially increased its support to the Gulf states in their campaign against the Iranian-backed Houthis. In Iraq and Syria, the process of rolling back Iran’s dominance will be more deliberate and long term.

After the missile strikes on Thursday, the US set a new standard for responding to the use of chemical attacks. Russia and the US will likely contain the fallout and engagement between the two countries might be even deeper, as happened between Turkey and Russia after the former downed a Russian jet in November 2015.

The outcome will not be a continuation of the current dynamics in Syria, but the beginning of a new chapter. It will be up to Washington and its ability to maintain the leverage it generated after the missile strikes to shape the outcome.

Hassan Hassan is the co-author of Isis: Inside the Army of Terror and a senior fellow at the Tahrir Institute for Middle East Policy