(CBSNEWS/AP) – North Korea’s state-run media claimed that the country has developed the ability to load a hydrogen bomb onto a new intercontinental ballistic missile, although some outside experts already cast doubts on the claim.

According to Pyongyang’s state media Korean Central News Agency, Kim Jong Un inspected the loading of a “homemade” hydrogen bomb onto the ICBM at North’s Nuclear Weapons Institute.

The explosive power of the bomb is adjustable from tens kiloton to hundreds kiloton,” the state run KCNA said.

But the Institute for Science and International Security, a U.S. non-profit dedicated to providing public knowledge of nuclear proliferation and international security, tweeted that North Korea can “build any H bomb (two stage) model it wants and call it whatever it wants but that does not make it real.” The non-profit also said “it looked like a model in a room for models.”

North Korea in July conducted its first ever ICBM tests, part of a stunning jump in progress for the country’s nuclear and missile program since Kim rose to power following his father’s death in late 2011.