A Russian fighter jet lands at Hemeimeem air base in Syria, Wednesday, January 20, 2016. Russian warplanes fly dozens of combat sorties a day, pressing Moscow's air blitz ahead of the scheduled Syria peace talks in Geneva. (Photo by Vladimir Isachenkov/AP Photo)





Russian air force personnel prepare to load humanitarian cargo on board a Syrian plane at Hemeimeem air base in Syria, Wednesday, January 20, 2016. (Photo by Vladimir Isachenkov/AP Photo)





A Russian soldier stands guard next to a bomber at Hemeimeem air base in Syria on Wednesday January 20, 2016. (Photo by Vladimir Isachenkov/AP Photo)





A Russian bomber, left, taxies out for a combat mission while another aircraft stand on the tarmac at Hemeimeem air base in Syria Wednesday January 20, 2016. (Photo by Vladimir Isachenkov/AP Photo)





A Russian bomber lands at Hemeimeem air base in Syria on Wednesday, January 20, 2016. (Photo by Vladimir Isachenkov/AP Photo)





A Russian bomber lands at Hemeimeem air base in Syria Wednesday, January 20, 2016. (Photo by Vladimir Isachenkov/AP Photo)





A Russian ground attack aircraft is prepared for a combat mission at Hemeimeem air base in Syria Wednesday January 20, 2016. (Photo by Vladimir Isachenkov/AP Photo)





A Russian air force technician attaches a bomb to a Russian ground attack jet at Hemeimeem air base in Syria on Wednesday, January 20, 2016. (Photo by Vladimir Isachenkov/AP Photo)





A Russian bomber taxies at Hemeimeem air base in Syria on Wednesday, January 20, 2016. (Photo by Vladimir Isachenkov/AP Photo)





A Russian air force technician reports to a pilot that a bomber is ready for a combat mission at Hemeimeem air base in Syria Wednesday January 20, 2016. (Photo by Vladimir Isachenkov/AP Photo)





A Russian helicopter gunship flies on patrol while air defense missile systems are seen in the background, bottom, at Hemeimeem air base in Syria Wednesday January 20, 2016. Russian warplanes have flown over 5,700 combat missions since Moscow launched its air campaign in Syria on September 30, 2015. (Photo by Vladimir Isachenkov/AP Photo)





A pair of Russian bombers being readied for action at Hemeimeem air base in Syria on Wednesday January 20, 2016. (Photo by Vladimir Isachenkov/AP Photo)





A Syrian air force technician directs the loading of humanitarian cargo on board a Syrian transport plane at Hemeimeem air base in Syria, Wednesday, January 20, 2016. (Photo by Vladimir Isachenkov/AP Photo)





A line-up of Russian bombers stand on tarmac as another plane takes off in the background at Hemeimeem air base in Syria on Wednesday January 20, 2016. (Photo by Vladimir Isachenkov/AP Photo)





Russian air force crew prepare a bomber for a combat mission at Hemeimeem air base in Syria on Wednesday January 20, 2016. (Photo by Vladimir Isachenkov/AP Photo)