MOSCOW – Russian President Vladimir Putin says modernized strategic bombers will boost the nation's military power.Speaking on a visit to an aircraft-making plant in Kazan Thursday, Putin said the revamped version of the Soviet-designed Tu-160 bomber features new engines and avionics that would significantly enhance its capability.The Russian leader attended the signing of a 160-billion-ruble (about $2.9-billion) contract that will see the delivery of 10 such planes to the Russian air force.