In this handout photo provided by the U.S. Navy, the USS Stout launches a Tomahawk missile in support of Operation Odyssey Dawn March 19, 2011. This was one of approximately 110 cruise missiles fired from U.S. and British ships and submarines targetting about 20 radar and anti-aircraft sites along Libya's Mediterranean coast.

Maj. Matt O'Donnell of Glenelg, MD shields himself from rotor wash as Ospreys carrying the delegation of U.S. Secretary of Defense Leon Panetta leaves on March 14, 2012 at Forward Operating Base Shukvani, Afghanistan. Panetta is also scheduled to meet with President Karzai during his two-day visit to Afghanistan. The trip comes as the Taliban has vowed revenge following this past weekend's killing spree by a U.S. soldier who is accused of killing 16 civilians in Afghanistan. Most of those killed were children and women. (Photo by Scott Olson/Getty Images)

South Korean military soldiers take part in the South Korea and U.S. joint military exercise to commemorate the 63th Korea Armed Forces Day at the Seungjin firing drill ground on September 30, 2011 in Pocheon, South Korea. The exercise is intended to prepare the South Korean defence force for any potential action from North Korea. (Photo by Chung Sung-Jun/Getty Images)

Nora Muaid stands in Zawraa Park on December 2, 2011 in Baghdad, Iraq. The park's 180-foot tall Ferris wheel opened earlier this year and is the second largest in the Middle East. (Photo by Mario Tama/Getty Images)

U.S. Army soldiers from the 2-82 Field Artillery, 3rd Brigade, 1st Cavalry Division, wait to load onto their armored vehicles as they prepare to convoy to Kuwait from Camp Adder in Iraq on December 7, 2011 at Camp Adder, near Nasiriyah, Iraq. (Photo by Joe Raedle/Getty Images)

Commander, a German Shepherd adult (L) and Ziva, a German Shepherd puppy attend as American Kennel Club announces Most Popular Dogs in the U.S. at American Kennel Club Offices on February 28, 2012 in New York City. (Photo by Gary Gershoff/Getty Images for AKC)

Vehicles pass through the heavy fog and air pollution that cover Skopje valley in the early morning, in Skopje, The Former Yugoslav Republic of Macedonia, 14 December 2017. According to media reports, Skopje is considered one of the most polluted cities in the world. (Photo by Georgi Licovski/EPA/EFE)

Two women look at a mobile phone as they stand on Tiananmen Square during a sand storm in heavily polluted weather in Beijing on February 28, 2013. Beijing residents were urged to stay indoors as pollution levels soared before a sandstorm brought further misery to China's capital. (Photo by Ed Jones/AFP Photo)