Ukrainian SU-27 planes fly over Ozerne air base, in Zhytomyr region in northern Ukraine, during a ceremony prior to the dispatch of Ukrainian troops to the east of the country, on December 6, 2018. (SERGEI SUPINSKY/AFP/Getty Images)
Soldiers exit their Puma armored personnel carrier of the German Bundeswehr during a training at the Bundeswehr infantry training facility on December 6, 2018 in Munster, Germany. Germany is increasing its annual defense budget following reports over recent years of a large portion of its military planes, ships, tanks and other weaponry as grounded due to lack of spare parts. (Photo by David Hecker/Getty Images)
The tanks Leopard 2 (R) and Puma (L) of the German Bundeswehr during a training at the Bundeswehr infantry training facility on December 6, 2018 in Munster, Germany. Germany is increasing its annual defense budget following reports over recent years of a large portion of its military planes, ships, tanks and other weaponry as grounded due to lack of spare parts. (Photo by David Hecker/Getty Images)
Ukrainian paratroopers stand to attention during a ceremony in Ozerne air base, Zhytomyr region in northern Ukraine, prior to their dispatch to the east of the country, on December 6, 2018. (SERGEI SUPINSKY/AFP/Getty Images)
U.S. Navy ceremonial guard HM2 Kenneth Knox stands over the the flag-draped casket of former President George H.W. Bush as members of the public line the route to pay their respects as the train carrying his body to his final resting place proceeds on December 6, 2018 in Texas. President Bush will be buried at his final resting place at the George H.W. Bush Presidential Library at Texas A&M University in College Station, Texas. A WWII combat veteran, Bush served as a member of Congress from Texas, ambassador to the United Nations, director of the CIA, vice president and 41st president of the United States. (Photo by Joe Raedle/Getty Images)
Graduates from the Indian Army's Jammu and Kashmir Light Infantry Regiment (JAKLI) take part in a passing out parade in Srinagar on December 8, 2018. - Some 259 graduates, many of them locals, completed a one year-training program prior to being absorbed as regular members of the regiment. (TAUSEEF MUSTAFA/AFP/Getty Images)
Saudi soldiers in armoured vehicles guard the entrance to the Diriya Palace in the Saudi capital Ryadh during the Gulf Cooperation Council (GCC) summit on December 9, 2018. - Riyadh is hosting the annual gathering as crises brew over the 18-month-old dispute with Doha, the war in Yemen and the murder of Saudi journalist Jamal Khashoggi in the kingdom's consulate in Istanbul. (NURELDINE/AFP/Getty Images)
Italian Air Force aerobatic team, performs in Kuwait City on November 17, 2018, as part of the celebration of the Italian week in Kuwait. (YASSER AL-ZAYYAT/AFP/Getty Images)
A picture taken on December 5, 2018, near the Israeli moshav of Zarit, shows Israeli Merkava tanks parked near the border with Lebanon, after the area was declared a closed military zone by the Israeli army. - Israel's army said earlier in the week that it has discovered Hezbollah tunnels infiltrating its territory from Lebanon and launched an operation to destroy them, a move likely to raise tensions with the Iran-backed group. (JALAA MAREY/AFP/Getty Images)