The United States has accused China and Russia of bearing “unique and special responsibility” for North Korea’s “belligerent” pursuit of nuclear weapons, after Pyongyang tested its latest ballistic missile. North Korea conducted its second intercontinental ballistic missile (ICBM) test late on Friday in what it called a warning to the “beast-like US imperialists”. It came less than a month after its first such experiment, on 4 July.