On Friday, the White House announced that President Trump will reluctantly sign a new sanctions bill targeting Russia. On Sunday, Russian President Vladimir Putin struck back.

He did so by ruling that the U.S. Embassy in Moscow must reduce its in-country staff by 755 employees. With the State Department employing around 1,200 individuals in Russia, Putin's ruling is significant. Indeed, the BBC reports that "This is thought to be the largest expulsion of diplomats from any country in modern history."

It will dramatically reduce the embassy's functionality.

Some might wonder why Putin is taking such drastic action. After all, Putin recently won major concessions from Trump when the pulled U.S. support for Syrian rebels. And with Trump showing broader malleability to Russian interests, Putin's rebuke seems ill-timed.

Except, that is, if you understand Putin's political psychology.

Ultimately, Putin's reflex is aggression. He knows Trump is only signing this bill under pressure from congressional Republicans. Correspondingly, by gutting the State Department's presence in Russia, Putin wants to strengthen Trump's argument that it is better to work with Russia rather than against it. Putin recognizes that his retaliation allows pro-U.S. Republicans to say, "See, we warned you Putin would hit back."

My response to that argument?

Putin's anger shows the sanctions are credible.

Moreover, the rationale behind these new sanctions is very clear. They offer a powerful response to a hyper-aggressive Russian espionage campaign against the U.S. And they're powerful for a good reason: They will dilute Russian energy influence in Europe. As I explained last week, this is what concerns Putin most. He knows that if he loses his ability to blackmail European nations with Russian energy supplies, his influence in the West will depreciate significantly.

Recognizing Putin's fears, U.S. policymakers should simply ignore his response. Were Trump or Congress to show weakness to Putin, he would only escalate.

Don't get me wrong: I'm not denying that these expulsions challenge U.S. diplomacy. Indeed, U.S. civil society and intelligence efforts in Russia are likely to suffer as the U.S. government finds a way to meeting Russia's employee cap. Nevertheless, when it comes to dealing with Putin, the second order effects are always more important.

And here, the second order effect of putting Putin on notice outweighs our declined diplomatic presence.

U.S. officials must refuse to blink. For the first time in a long time, U.S. policymakers have rebuffed Putin with strength. It's a prerequisite for any serious Putin compromises in the future.