When air power works, and when it doesn’t: A snapshot of U.S. operations against the Islamic State; 2,900 explosions in a day. Heavy artillery and tank fire returns to the front lines in Ukraine.; Army veteran Vincent Viola, billionaire owner of the Florida Panthers, named Trump’s Army secretary; Pentagon: China will return naval drone seized in South China Sea to U.S.;   A military blog by Dan Lamothe   When air power works, and when it doesn’t: A snapshot of U.S. operations against the Islamic State With Mosul, sophistication of enemy and size of the city make for a tough fight. By Missy Ryan and Loveday Morris  •  Read more » ADVERTISEMENT   2,900 explosions in a day. Heavy artillery and tank fire returns to the front lines in Ukraine. It was the bloodiest day for the Ukrainian military in five months. By Thomas Gibbons-Neff  •  Read more »   Army veteran Vincent Viola, billionaire owner of the Florida Panthers, named Trump’s Army secretary Viola funded the highly regarded Combating Terrorism Center at West Point, N.Y. By Dan Lamothe  •  Read more »   Marine Corps withheld suicide investigation results that suggested drug use among Marines A Marine spokesman said the breakdown was in 'no way intentional.' By Dan Lamothe  •  Read more »   Pentagon: China will return naval drone seized in South China Sea to U.S. The underwater drone was being used by the U.S. Navy to test water conditions in international waters, the Pentagon said Friday. This is a developing story. It will be updated.   By Washington Post Staff  •  Read more » ADVERTISEMENT   Recommended for you   WorldViews Important stories from around the world, in your inbox daily. Sign Up »         Share Checkpoint:       Twitter      Facebook Trouble reading? Click here to view in your browser. You received this email because you signed up for Checkpoint or because it is included in your subscription. For additional free newsletters or to manage your newsletters, click here. We respect your privacy. If you believe that this email has been sent to you in error or you no longer wish to receive email from The Washington Post, click here. Contact us for help. ©2016 The Washington Post, 1301 K St NW, Washington DC 20071