Marines from 1st Battalion, 4th Marines, conduct a night assault on targets at Al Qatrana, Jordan, during the Infinite Moonlight exercise in 1998. JO1 Craig P. Strawser/Newscom/File
A US soldier of 2-12 Infantry 4BCT-4ID Task Force Mountain Warrior takes a break during a night mission near Honaker Miracle camp at the Pesh valley of Kunar Province, Afghanistan on Aug. 12, 2009. Carlos Barria/Reuters/File
A soldier from the US Army's 1st Platoon, Alpha Troop, 2-1 Infantry Battalion, 5/2 Striker Brigade Combat Team scans the area with a scope during a night observation mission in the Arghandab River Valley in Kandahar Province on April 15. Tim Wimborne/Reuters
Seen through a night-vision device, US Army Cpl. Shaun Armstrong secures a landing zone during an air assault mission during Operation Champion Sword in Khost province, Afghanistan, on Aug. 2, 2009. Matthew Freire/DOD/Sipa Press/Newscom/File
US Army soldiers of B Company, 3rd Battalion 82nd Combat Aviation Brigade hold a mission briefing on board their CH-47 helicopter as they ready for a night mission at Kandahar Airfield, Afghanistan, on Sept. 1, 2009. Zuma/Newscom/File
Seen through night-vision optics, US Army Special Operations Forces interrogate the son of a suspected al-Qaida cell leader during a raid on his compound, on Sept. 4, 2002, in the village of Ayul-Kheil outside of Khost, 90 miles southeast of Kabul. Wally Santana/AP/File
Brazilian-born US marine Corporal Felipe Carvalho Barbosa, from High Point, N.C., talks with a comrande as he checks a light on his weapon before leaving for a night foot patrol in Fallujah, Iraq, in Dec. 2005. Mauricio Lima/AFP/Getty Images/Newscom/File
During a nighttime medevac mission over Marjah, Afghanistan, US Army 82nd Airborne's All American Dustoff flight medic Sgt. John Collier attends to his patient, an Afghan interpreter on March 6. The crews of Pegasus med and chase birds fly together on missions, 24 hours a day, seven days a week, providing fast medical evacuation to wounded combatants and civilians from often hostile situations in Afghanistan. Brennan Linsley/AP
Sgt. Jeff Grothause, 10th Mountain Division, 1st Battalion, 87th Infantry Regiment, prepares for a live-fire drill conducted in darkness at Fort Drum, New York. Technology allows soldiers to operate in the night, giving them a critical advantage. Andy Nelson/The Christian Science Monitor/File
A US Army soldier guards a detainee during an air assault mission during Operation Champion Sword in Khost province, Afghanistan, Aug. 2, 2009. Matthew Freire/DOD/Sipa Press/Newscom/File
U.S. Marines from the 2nd MEB, 1st Battalion 5th Marines board helicopters at Camp Leatherneck for a night air assault in Afghanistan's Helmand province on July 2, 2009. David Guttenfelder/AP/File
A combat photographer with Command Element, 11th Marine Expeditionary Unit (Special Operations Capable), photographs Marines from the 1st Battalion, 4th Marine Regiment, 11th MEU as they respond to a night ambush set by insurgents in An Najaf, Iraq, on Aug. 8, 2004. Cpl. Dick Koteck/USMC/Newscom/File
Airman 1st Class Justin Cole, Tech. Sgt. Marcus Cottengim and Chief Master Sgt. Roy Cupper conduct a pre-flight inspection on an MQ-1 Predator unmanned aerial vehicle prior to a night mission from Ali Air Base, in Iraq on Nov. 5, 2007. Jonathan Snyder/USAF/UPI/Newscom/File
An outburst of violence in recent days between the Dinka and the Nuer in Sudan could portend civil war in the country, officials warned Wednesday. President Salva Kiir accuses rival Riek Macharf of sparking the violence, but says he is willing to begin a dialogue.
South Sudan's army said it had lost control of the flashpoint town of Bor on Wednesday, its first acknowledged reversal in three days of clashes between rival groups of soldiers that have triggered warnings of a slide into civil war.