NarrowBandFtw
Honorary Master
You mean like this? https://www.rt.com/news/332410-us-urges-turkey-shelling/
Not quite, it certainly is a start, but it is the same kind of language used when Turkey shot down a Russian plane. "Urging", "we are concerned" etc
Clearly the diplomatic approach is not effective when it comes to Turkey and the US holds some real power over Turkey. They could easily just announce a suspension to Turkey's NATO membership until a future date.
Letting them officially know they are acting alone instead of leaving it open to interpretation. Or they could get the UN security council involved in an official capacity, joining the action, not just condemning the violence etc etc
If they talk nicely and patiently wait for Turkey to do the sensible thing it is bound to spiral out of control.