The United States said it was flying training missions of nuclear-capable B-52 bombers over South Korea, in a clear signal to North Korea at a time of escalating military tensions. The flights - part of annual joint South Korea-US military exercises - should be seen as underscoring US commitment and capacity to defend Seoul against an attack from the North. The Boeing B-52 was designed to carry nuclear weapons for Cold War-era deterrence missions. The bomber carries up to 31 tons of weapons. The zenith of B-52 attacks in Vietnam was Operation Linebacker II which consisted of waves of B-52s. Over 12 days, B-52s flew 729 sorties and dropped 15,237 tons of bombs in Vietnam. The B-52 strikes were an important part of Operation Desert Storm. With about 1,620 sorties flown, B-52s dropped 25,000 tons of bombs. The B-52 also contributed to Operation Enduring Freedom in Afghanistan. The B-52s are capable of carrying 24 2000 pound bombs that are capable of destroying underground facilities. If the B-52s are deployed and used against North Korea, it will literally rain hell on North Korea.