Why do you think this is to depressurize? Saddam thought the same thing in the 90s. Turns out his weakness and refusal to strike back made sure America continued to soften him up until his military was in ruins and his people starving.
You know, a very small part of me is happy this happened. A lot of people, even among the pro-Axis club, always held Russia as this huge bulwark against western aggression. They couldn't stop talking about how Putin is a chess player and the Russian bear has awoken from his slumber. They'd relegate Iran to a second-rate ally to Syria. Well, now who the hell is the second-rate ally? Trump called Russia's bluff and Russia didn't do anything. Iran might not have the assets Russia has, but it is a more honourable ally.
My take on this is that in the last week extra-ordinary pressure AND self-interest surfaced in the current US administration to compound for a symbolic strike like this. There were a couple of reasons for that.
1. one-upping the Obama administration, supporting the rhetoric that the current administration is not weak or feeble.
2. alleviating allegations of collusion with Russia.
3. changing the national conversation to obfuscate a number of running scandals (Comey's book, the raid on Cohen, Mueller's probe).
4. Consolidating republican leadership and legislature around the POTUS.
Remember, the current administration was voted in on a non-intervention nationalistic platform. It has been one week or so that the current POTUS proclaimed a policy decision and shift towards leaving Syria.
As I had said at the time military entanglement came to the table just after the chemical attacks,
it is both improbable and unwarranted for Russia to escalate against NATO forces if its own forces at the field are not attacked. At the same time, I said that NATO forces will offer a token/symbolic action, because
it is impossible for them to actually hurt Assad in a quantitatively significant way, as long as Russia and Iran are strongly in the mix in Syria.
I honestly think that the fact these strikes were
(1)duly announced days before,
(2)concentrated on a constructed and targeted messaging campaign about chemical weapons,
(3)were designed and executed in a way that eliminated Russian escalation or substantive Assad regime harm and
(4)included Britain and France for messaging purposes, really supports my argument.
RealPolitik-wise, this was a posturing campaign to validate Western Exceptionalism, not a significant move towards the civil war or against the Assad Regime.
Cheers.