Pakistan selling nuclear materials to North Korea is an obvious concern. North Korea is a rogue state that can't be trusted to comply with any treaty, so the only real security against North Korea producing nuclear weapons is the fact that the country is technologically backward. If a larger power helps North Korea out, maybe that could negate North Korea's problems with technology and lead to a rogue state getting nuclear weapons.
Pakistan selling nuclear materials to North Korea should be something of grave concern to the United States because North Korea is a threat to the world peace. In recent days, South Korea has made its intentions of using the nuclear weapons clear with numerous testing of the same and blatantly violating the UN guidelines of handling nuclear weapons.
The United States, as well as the world community as a whole, should be concerned by the news that Pakistan is selling nuclear materials to North Korea. Although there are some valid, non-weaponised, uses for nuclear materials there is still an increased risk to world peace if these are sold to North Korea.
The United States should be deeply concerned over the report that Pakistan has been selling nuclear materials to North Korea. North Korea is an unstable, dangerous, isolated nation that has shown strong hostility toward its neighbors. Pakistan, nor any other country should be providing nuclear materials to the North Koreans. The United States should be concerned about this troubling report.