The United States Secretary of State John Kerry started his Asia tour with Laos, the 2016 chair of the 10-nation Association of Southeast Asian Nations (ASEAN), on Monday.
Laos wants to see maritime rights protected and avoid a militarisation and conflict in the South China Sea, Kerry said after a meeting with Laos' Prime Minister Thongsing Thammavong.
"He [Thammavong] was very clear he wants a unified ASEAN and he wants maritime rights protected, and he wants to avoid militarisation and to avoid conflict," he said.
China claims almost all of the energy-rich waters of the South China Sea, through which more than $5 trillion of maritime trade passes each year. Several ASEAN states have overlapping claims.
Laos has close political and economic ties with China, which prompts Washington to worry that it might behave like Cambodia did when it was the ASEAN chair in 2012.
Cambodia was accused of preventing consensus in the bloc over standing up to China's South China Sea claims.
"It is particularly important that Laos finds itself playing a critical role within ASEAN, and ASEAN itself is critical to upholding the rules-based system in the Asia-Pacific and ensuring that every country, big and small, has a say in addressing the matters of shared concern," Kerry said.
In February, US President Barack Obama will host a special ASEAN summit in California.
Obama will also be the first US president visiting the resource rich but impoverished communist state, when he attends the ASEAN 2016 summit in Laos later in September.
Kerry’s Laos visit was only the third visit by a US Secretary since 1955.
His tour included Switzerland and Saudi Arabia before his Asia visits, and Cambodia later on Monday.
He last stop will be China, where Kerry is expected to stress the need for a united front in response to this month's North Korean nuclear test through additional UN sanctions and for a tough unilateral response from China, North Korea's main ally and neighbour.
An estimated 30 percent of unexploded US bombs remain in Laos -the most bombed nation in the world per capita- since the Vietnam War, which killed around 50,000 people after the war.
Kerry said the US had increased funding from $5 million to $15 million this year for the demining over the years and that it is “looking at whether or not that could be plussed up even more."
300 people used to die of the ordnance until a few years ago, and it has fallen to about 50 deaths a year. But "Fifty a year is still too many," Kerry said.