Some thoughts on the US's decision to sanction for its purchase and activation of Russia's S400 air defense system: https://abcnews.go.com/Politics/us-sanctions-turkey-purchasing-russian-missile-system/story?id=74672022

The decision is a long-time coming. After Ankara's purchase of the S400, Congress pushed Trump to impose sanctions. He tried to avoid imposing them, but this week Congress passed legislation mandating sanctions, forcing his hand.

Sanctions target Turkey's Presidency of Defence Industries, a body under the aegis of Turkey's defence ministry handling procurement. Crucially, they include an export ban, along with measures targeting key officials.

Much will depend on implementation but the measures don't seem light. Turkey's defence industry relies on Western suppliers. Sanctions will make it harder for Turkey to get hold of equipment sourced from US, or containing US components. This potentially involves European firms

Sanctions will further poison US-Turkey relations. They won't be easy to remove: the legislation that pushed Trump to enact them ties them to Turkey giving up the S400. Clear risk that sanctions may push Turkey to source more equipment from Russia.