The US president Donald Trump has urged Vietnam to buy missiles and other weapons systems from the United States.

The US president delivered a message to Prime Minister Nguyen Xuan Phuc, urging him to buy missiles and other weapons systems from the United States. Trump said the US "makes the greatest missiles in the world" during his brief state visit to Vietnam.

Trump had also offered at an earlier meeting on Sunday with Vietnamese President Tran Dai Quang to serve as a mediator in the South China Sea territorial disputes.

But during a joint appearance with President Trump, Quang said his country wants to settle disputes in the South China Sea through peaceful negotiations.

Vietnam and China along with four others claim all or parts of the strategic waters.

Chinese President Xi Jinping is scheduled to arrive in Vietnam for a state visit later on Sunday. Disputes over the South China Sea are expected to be high on the agenda during Xi's talks with Vietnamese leaders.

Trump has highlighted trade issues in meetings with Vietnam's prime minister and the secretary-general of its Communist Party.

Trump told Communist Party leader Nguyen Phu Trong that trade had become a very important element in the relationship between the two countries.

Outside of trade, Trump says he looks forward to the onetime adversaries, the US and Vietnam, having a fantastic relationship for years to come.