We do everything humanly possible, consistent with military necessity, taking many chances to avoid civilian casualties, at all costs.

I was struck by the fact that none of the senators, basically, asked General [James] Mattis, "Well, General, how is it that we haven't won?" We haven't won anywhere, 'winning' in the sense of conclusively achieving our political objectives, however you might want to define those objectives.

I think the core problem is much closer to recognizing where force is of value, where it is useful, and to distinguish that from situations in which war is not useful or is indeed counterproductive.

I would consider the principal threats to start with Russia. And it would certainly include any nations that are looking to intimidate nations around their periphery, regional nations nearby them, whether it be with weapons of mass destruction or I would call it unusual, unorthodox means of intimidating them.

Our strategy right now is to accelerate the campaign against ISIS. It is a threat to all civilized nations.

Treachery has existed as long as there's been warfare, and there's always been a few people that you couldn't trust.

When you're in operations, the best thing you can do at the top level is get the strategy right. You have to get the big ideas right, you have to determine what is the policy, what is the level of effort you're willing to commit to it? And then you delegate to those who have to execute that strategy to the appropriate level. What's the appropriate level? It's the level where people are trained and equipped to take decisions so we move swiftly against the enemy.