James Stavridis is a retired four-star U.S. Navy admiral and NATO supreme allied commander who serves today as the dean of the Fletcher School of Law and Diplomacy at Tufts University. His latest book is
The Leader's Bookshelf.
KORENGAL VALLEY, AFG - OCTOBER 27: U.S. soldiers board an Army Chinook transport helicopter after it brought fresh soldiers and supplies to the Korengal Outpost October 27, 2008. The military spends huge effort and money to fly in supplies to soldiers of the 1-26 Infantry based in the Korengal Valley, site of some of the fiercest fighting of the Afghan war. The unpaved road into the remote area is bad and will become more treacherous with the onset of winter. (Photo by John Moore/Getty Images)
TOPSHOT - Cuban Americans in Miami's Little Havana celebrate the death of longtime Cuban leader Fidel Castro on November 26, 2016.
Cuba's socialist icon and father of his country's revolution Fidel Castro died on November 25 aged 90, after defying the US during a half-century of ironclad rule and surviving the eclipse of global communism. / AFP / RHONA WISE (Photo credit should read RHONA WISE/AFP/Getty Images)
A computer running a Windows Server is seen connected into a network server in an office building in Washington, DC on May 13, 2017.
International investigators hunted on May 13 for those behind an unprecedented cyber-attack that affected systems in dozens of countries, including at banks, hospitals and government agencies, as security experts sought to contain the fallout. The assault, which began Friday and was being described as the biggest-ever cyber ransom attack, struck state agencies and major companies around the world -- from Russian banks and British hospitals to FedEx and European car factories. / AFP PHOTO / Andrew CABALLERO-REYNOLDS (Photo credit should read ANDREW CABALLERO-REYNOLDS/AFP/Getty Images)
HEMPSTEAD, NY - SEPTEMBER 26: Republican presidential nominee Donald Trump waves after the Presidential Debate with Democratic presidential nominee Hillary Clinton at Hofstra University on September 26, 2016 in Hempstead, New York. The first of four debates for the 2016 Election, three Presidential and one Vice Presidential, is moderated by NBC's Lester Holt. (Photo by Drew Angerer/Getty Images)
ANNAPOLIS, MD - JULY 01: Incoming U.S. Navy plebes, or freshmen, are taught how to salute on their first day at the U.S. Naval Academy July 1, 2015 in Annapolis, Maryland. Over 1,193 Plebes will be processed through various stations that will culminate with the Oath of Office ceremony to become members of the Naval Academy's Class of 2019. (Photo by Mark Wilson/Getty Images)