Even before he took over as head of US Pacific Command last May, Admiral Harry Harris had distinguished himself as one of the more hawkish observers of China’s rapid-fire construction of artificial islands in the South China Sea. “China is creating a Great Wall of sand,” he said in March 2015.

The admiral’s plain speaking has at times placed him at odds with the White House, which for all its confident rhetoric on President Barack Obama’s visit to Vietnam this week has tied itself in knots over how forcefully the US should challenge China’s growing presence and ambitions in the South China Sea.

The sharp-tongued, Japan-born Adm Harris has led a private and occasionally public campaign to get the White House to take a more confrontational stance, according to US officials.