Russian Tu-160 bombers, like the one pictured above, have been involved in massive attacks against Ukraine in recent months.Russian Defense Ministry Press Service via AP, FileRussia has changed the way it attacks Ukraine with missiles and drones in recent months.Since August, Russia has likely been conserving its munitions for larger but less frequent attacks.Britain's defense ministry said this strategy differs from Russia's approach earlier this year.Russia is likely conserving its missiles and building up stockpiles to launch larger — but less frequent — attacks on Ukraine, according to a new Western intelligence assessment.The Russian military has launched several big aerial bombardments against Ukraine this month, including one large-scale attack that saw Moscow fire more than 90 missiles and 190 drones at its neighbor.