US President Donald Trump has returned from a historic, impromptu stop on North Korean soil to attacks from Democrats and suggestions of a rift within his administration, with critics saying he is normalizing a nuclear-armed Pyongyang. In the sort of made-for-television, down-to-the-wire diplomacy relished by the former reality television host, Trump walked a few paces across the Demilitarized Zone on Sunday to greet North Korean leader Kim Jong Un, a day after the US leader proposed a meeting over Twitter. In practical terms, Trump said that he and Kim agreed to start working-level talks on a denuclearization deal, ending a standstill in place since the two leaders' second summit, in Hanoi in late February, ended without an agreement.