With its sanctioning of Cambodian officials and warnings not to invest in the country, Washington’s increased pressure on Phnom Penh not only risks alienating it but undermining Asean centrality, say observers.

Two US-built structures at Ream were razed last year, sparking concerns that China will benefit from upgrades to the base.

The symbolic relationship with Beijing is strategic for the royals, as their future is uncertain given previous tension with the Cambodian government.

Chinese foreign minister Wang Yi will meet Cambodia’s PM Hun Sen as part of a diplomatic drive in Southeast Asia amid the growing US-China rivalry.