This week on Facing the Future, we speak with Michael O'Hanlon of the Brookings Institution for an assessment of US national security strategy from Ukraine to China, the Arctic, and everything in between. And, what this means for future US defense spending, which is a significant part of the federal budget. O'Hanlon has served as an advisor to both the Defense Department and the CIA, and gives us a preview of his new paper assessing the Pentagon's budget needs relative to the global threats and challenges we face. Also we'll take a look at how a few small changes to economic assumptions make major changes in long-term projections for the federal budget and our national debt.