WASHINGTON — With China accelerating its military modernization, Russia continuing its slow-drip incursion into Ukraine, and an expanding section of the Middle East devolving into chaos, it has once again become fashionable to argue that the United States is in decline. Strangely, Americans are often far quicker to accept this diagnosis than their counterparts abroad.

Dear Mr./Ms. President:

Each of your predecessors has had to confront crises, at home and abroad, and, especially in the last third of our nation’s history, each has had to respond to events and trends abroad that could affect vital interests.  You will doubtless have to do so as well.