What Russia has said in response to US missile attacks on Syria has so far been entirely predictable. It is what Russia will do in response that provides uncertainty. But that uncertainty is not one-sided. The sudden policy reversal by the United States has demonstrated beyond doubt that it is not only President Putin that can be unpredictable; President Trump can match him.
This lays the basis for a fundamental change in how Russia views its relationship with the United States. Whereas previously President Trump appeared to be implementing Russian policy for the US, whether consciously or unconsciously, the Syria strikes suggest that he cannot be relied on to do so consistently. In demonstrating clearly what conduct is unacceptable to the United States, Trump has departed completely from practice by the previous administration. President Obama's predictable disinclination to enforce red lines or respond to Russian assertiveness invited Moscow to ever more blatant hostile activities. Now, Russia will be forced to at least consider the possibility that its actions may have costs and consequences imposed by the United States.
In this way, the use of military force against Syria provides a degree of reassurance for other states around the world whose security relies on the United States being prepared to counter Russian offensive moves. To some small extent it does resolve the doubt over whether the United States will now be willing to resort to force in the defence of third parties' interests. In particular, despite the restraint displayed by the United States in warning Russia of the impending strikes in order to avoid Russian casualties and the risk of direct conflict with Russia (but also allowing Russia to warn Syria and minimise damage), the speed of response by Washington may have got inside the Kremlin's military and political decision loop, and achieved a degree of operational if not tactical surprise. There may have been restraint on both sides: it is suggested that Russia chose deliberately not to test its anti-missile defence systems in place in Syria against the incoming US cruise missiles.
In other ways Russia is making maximum use of the attack for its own purposes. Its protests against aggressive action by the United States will in no way be constrained by Russia's own track record of not only causing mass casualties in Syria through its own actions, but also launching large-scale aggressive action against its immediate neighbours. Russia's calling for an emergency meeting of the UN Security Council is a formal necessity, though it is unclear how much traction Russia will gain there given its dismal performance defending the indefensible in Syria over the last week. Potentially more seriously, Russia has suspended the agreement with the United States intended to de-conflict air movements over Syria. This paves the way for a return to aggressive manoeuvring by Russian pilots testing the both the capabilities and restraint of Western and Israeli aircraft, and in particular it means that "misunderstandings" and accidental engagements can take place with deniability between Russian and other aircraft.
Finally, the strikes are a gift to Russia for reinforcing its own domestic narrative convincing its population that it is under imminent threat from an aggressive and unrestrained West which might well launch similar strikes against Russia itself. While this idea is not new, it has until now been based entirely on fantasy and a fundamental misreading of US intentions. But after assertive US action in Syria, Russian security planners must consider the distant possibility that the United States might be willing to deter Russia itself by punishment as well as by prevention.