North Korea conducted a failed missile test Thursday — its second in a week — of what was believed to be a powerful medium-range Musudan, the U.S. and South Korea said.

Such a weapon could threaten military installations on Guam and the U.S. nuclear bombers deployed there that play a key role in deterrence on the Korean Peninsula.

Some experts have warned that the Musudan could become operational as early as next year amid the North's ramped up missile tests.