US Army soldiers fire blanks during military exercises near Pabrade, Lithuania, on Thursday, November 24. About 4,000 soldiers from different NATO countries took part in the two-week exercises. Sean Gallup/Getty Images

A US helicopter prepares to land on the USS Dwight D. Eisenhower on Saturday, November 24. The aircraft carrier was in the 5th Fleet area of operations, which includes the Persian Gulf, the Red Sea, the Arabian Sea and parts of the Indian Ocean. Petty Officer 3rd Class Nathan T. Beard/u.s. navy

Glen Newton, a member of the US Air Force, visits the Denver grave of his grandfather Joe Bolton on Veterans Day, Friday, November 11. Bolton, a former Army captain, died in October. John Leyba/The Denver Post via Getty Images

US Sen.-elect Tammy Duckworth, an Iraq war veteran who lost both of her legs in a helicopter crash, leaves the Capitol after the Senate Democratic Caucus held leadership elections on Wednesday, November 16. Tom Williams/CQ Roll Call/getty images

Japan's Mount Fuji is seen in the background as Osprey aircraft return from a training exercise on Friday, November 4. Sergeant Major Michael Cato/u.s. marines

A US Coast Guard boat passes through the Mar-a-Lago resort where President-elect Donald Trump was spending his Thanksgiving holiday in Palm Beach, Florida, on Thursday, November 24. Gerardo Mora/Getty Images

US military personnel wait in line for Thanksgiving dinner at a coalition air base in Qayyara, Iraq. Felipe Dana/AP

A military helicopter helps fight a wildfire in Pickens County, South Carolina, on Thursday, November 10. South Carolina National Guard

Gail Halvorsen, a former US Air Force pilot who is famous for dropping candy to children during the Berlin Airlift, is seen in front of a military transport plane in Frankfurt am Main, Germany, on Monday, November 21. Halvorsen was at Frankfurt's airport for the rededication of its Berlin Airlift Memorial. BORIS ROESSLER/AFP/Getty Images

US jets fly over CenturyLink Field before an NFL football game in Seattle on Sunday, November 20. Otto Greule Jr/Getty Images

American and Chinese soldiers participate in a mock rescue during an earthquake drill in Kunming, China, on Friday, November 18. Andy Wong/AP

US Secretary of State John Kerry prepares to board a plane as he leaves Antarctica on Saturday, November 12. MARK RALSTON/AFP/Getty Images

US Rep.-elect Brian Mast, a former Army soldier who lost both his legs in Afghanistan, walks down the House steps before posing for a group photo in Washington on Tuesday, November 15. Chip Somodevilla/Getty Images

Vice President Joe Biden, center, watches an Army team carry the remains of Pfc. Tyler R. Iubelt at Dover Air Force Base in Delaware on Tuesday, November 15. Iubelt, a 20-year-old from Tamaroa, Illinois, was killed by an improvised explosive device while serving in Afghanistan. Steve Ruark/AP

A member of the color guard pauses during a Veterans Day ceremony at Arlington National Cemetery on Friday, November 11. Veterans honored around the world Carolyn Kaster/AP

US Marines take part in cold-weather training in Blatind, Norway, on Thursday, November 3. Sgt. Michelle Reif/u.s. marines

US Marines, US sailors and Cambodian sailors disembark from an amphibious landing craft during a training exercise in Sihanoukville, Cambodia, on Thursday, November 3. Chief Petty Officer Lowell Whitman/u.s. navy

A French military helicopter, left, and a US military helicopter participate in a training exercise in La Teste-de-Buch, France, on Wednesday, November 9. MEHDI FEDOUACH/AFP/Getty Images

US Secretary of Defense Ashton Carter watches a hostage-rescue training exercise near Hurlburt Field, Florida, on Thursday, November 17. Devon Ravine/Northwest Florida Daily News via AP

A US Army helicopter lands in Qayyara, Iraq, on Saturday, November 19. American troops are part of an Iraqi-led coalition trying to retake the city of Mosul from ISIS militants. Mosul operation: Iraqi-led forces push into key city Senior Airman Jordan Castelan/u.s. air force

Gold Star mothers listen to President Barack Obama speak during a Veterans Day ceremony in Arlington, Virginia, on November 11. Pablo Martinez Monsivais/AP