US President Donald Trump has offered his services as a "mediator and arbitrator" over disputed territorial claims South China Sea issue, one of the most pressing issues for many of Asia's leaders. Speaking to his Vietnamese counterpart, Tran Dai Quang in Hanoi, Trump said he could employ his diplomatic skills to help Asian nations come to an agreement over competing maritime claims. "I can help mediate and arbitrate. Please let me know," Trump said. "I know you've had a dispute for quite a while with China, if I can help in any way, I'm a very good mediator and a very good arbitrator."