MOSCOW, May 27 (Xinhua) -- Russian arms export corporation Rosoboronexport signed a contract with the U.S. Army Forces Command on supplying 21 Mi-17V5 multipurpose helicopters to Afghanistan, a spokesman for the Russian Federal Service of Military-Technical Cooperation said on Friday. The United States and Russia have been in talks for more than a year on the deal to provide the much-needed vehicles for the NATO mission in Afghanistan, RIA Novosti reported. The cost of one helicopter has been agreed earlier at 17.5 million U.S. dollars. The first helicopters will be sent to Afghanistan in October 2011, said the spokesman. Besides,...