Defense Minister Kim Kwan-jin on Sunday claimed North Korea's failed rocket would, if successful, have a range of 10,000 km, which would make it capable of reaching the west coast of the U.S. Kim told the National Assembly's Defense Committee, "We have discussed that this one was probably upgraded to fly about 10,000 km."
The rocket is 30 m long and has a diameter of 2.5 m, similar to a rocket launched in April 2009, which was 32 m long and had a 2.2 m diameter. But the new rocket is 13 tons heavier at 92 tons.
Rocket experts believe that North Korea tried to put in more fuel with an improved engine in order to increase liftoff thrust. The previous rocket was said to have a range of 6,700 km, which would make it just capable of reaching Alaska, but the South Korean military speculates that the North worked on improving the range.
Meanwhile, indications are that the rocket exploded 55 seconds earlier than initially reported, namely two minutes and 15 seconds after launch. A source in the South Korean government said, "There was a strange occurrence that looked like an explosion at 50 km above sea level around one minute and 20 seconds after the launch. The rocket continued to fly thanks to thrust and inertia, and at two minutes and 15 seconds, at 70.5 km above sea level, it split in two."
The first-stage rocket thus probably exploded one minute and 20 seconds after launch, so the cause is now more likely to have been a flawed engine or fuel leakage from the first-stage rocket.