President Donald Trump has invited his hardline Philippine opposite number Rodrigo Duterte to the White House in a sharp change from almost a year of fraught relations between Washington and its crucial Southeast Asian security ally.

While Mr Duterte called President Barack Obama a “son of a whore” and told him to “go to hell” after the US criticised his bloody drugs war — in which thousands of people have died — the Trump administration said the Philippine leader was “fighting very hard” against the “scourge” of narcotics.

Mr Trump followed up with invitations to the prime ministers of Thailand and Singapore as part of a broader regional outreach, partly in response to tensions between the US and North Korea. The US president’s weekend calls to the three leaders also came amid further signs of how China’s growing power in Asia — including improved relations with the Philippines under Mr Duterte — are helping Beijing tighten its control of disputed seas.