The United States on Friday froze the assets of a North Korean bank after the Treasury Department designated it a proliferator of weapons of mass destruction. The Amroggang Development Bank is controlled by North Korea"s Tanchon Commercial Bank, an institution already blacklisted and sanctioned by Washington, the Treasury said. "As long as North Korea continues to try to evade sanctions and obscure its illicit proliferation transactions, we will take steps to combat that activity and protect the integrity of the international financial system," said Stuart Levey, the department"s anti-terrorism chief.