2. North Korea will send a 140-piece orchestra to perform in the Winter Olympics in South Korea, beginning next month. It represents another step in the astonishing ratcheting down of tensions between the neighbors.

But North Korea’s nuclear program remains a concern. While American officials, including Defense Secretary Jim Mattis and Gen. Joseph F. Dunford Jr., chairman of the Joint Chiefs of Staff, say they are committed to finding a diplomatic resolution, they are not taking any chances.

The U.S. military has begun conducting exercises across the country (above, in Fort Bragg, N.C.) — preparations for a war that military leaders hope never comes.