Is Trump Taking Control?

Haberman, but also smart people like Digby and Yglesias are saying this: 

Trump has discovered his power and he's conducting a purge of his enemies. Finally firing Tillerson is consistent with his recent manic, agitated behavior and reports that he's decided to "go with his gut." As I wrote in this piece last week presidential power is mostly concentrated in foreign policy and national security and (other than expanding the death penalty) that is where Trump has been focused for 30 years. He's going to "make them stop laughing at us."

I’m skeptical. There’s only so much he can do without getting cooperation from someone else in the Executive Branch.  

The model is the tariff tweet. It seems like that was him on his own and Ross backed him up. Will it work like that on the Iran Deal? 

Can he do something domestically? The President has free rein with foreign policy, but domestic policy is much less centralized.  

I don’t know.