A contentious Chinese high speed rail project in Thailand has emerged as an important test of both Beijing’s regional ambitions and the appetite of the ruling generals in Bangkok for deeper ties with their giant neighbour.

Questions swirl around the scope, cost and viability of a plan that critics have branded the “Train to Nowhere” after the two countries said they wanted to push ahead with a $5.2bn first phase but pointed to initial construction of only 3.5km of track. 

The project is part of a wider pivot by China to Southeast Asia as it seeks to build trade routes, exploit tensions with Washington, and quell opposition to its sea territory claims. But the Mekong rail initiative has also been plagued by delays and disagreements that highlight wider regional obstacles to Chinese dominance and its “One Belt, One Road” trade route strategy of investing in infrastructure in neighbouring countries — as well as those farther away.