Vietnam's military is steeling itself for conflict with China as it accelerates a decade-long modernization drive, Hanoi's biggest arms buildup since the height of the Vietnam War.

The ruling Communist Party's goal is to deter its giant northern neighbor as tensions rise over the disputed South China Sea, and if that fails, to be able to defend itself on all fronts, senior officers and people close to them said.

Vietnam's strategy has moved beyond contingency planning. Key units have been placed on "high combat readiness" — an alert posture to fend off a sudden attack — including its elite Division 308, which guards the mountainous north.