US President Donald Trump and South Korea's leader Moon Jae-In today agreed to remove limits on the payload of the South's missiles, as the UN Security Council met to discuss a response to Pyongyang's sixth and most powerful nuclear test.<br/>'<br/>The two leaders in a phone call "agreed to lift the cap on missile payload of South Korea as an effective countermeasure" against Pyongyang's test on Sunday of what it described as a hydrogen bomb designed for a long-range missile, the presidential office said in a statement.<br/>'<br/>Seoul was perviously restricted to a maximum warhead weight of 500 kilogrammes on its ballistic missiles, according to a bilateral agreement with the United States. <br/><br/>