When it comes to U.S. security interests in Europe, the Pentagon must balance military needs with the need for NATO allies to do more.

That concern is again relevant following Senate testimony on Tuesday in which America’s top military officer in Europe called for more military assets to be delegated to his command. General Curtis Scaparrotti, who is also NATO’s supreme commander, says he needs more intelligence assets and two more destroyers, to add to the four already present. And Scaparrotti was clear with the senators.”I am not comfortable yet with the deterrent posture that we have in Europe,” he said.