Vietnam’s navy has conducted live-fire artillery drills off the country’s central coast following increased tensions with China over control in the South China Sea.

The naval exercises began near an unoccupied island 40 kilometers from Vietnam’s central coast, in an escalation of tensions between Vietnam and China over disputed waters within the South China Sea.

Vietnamese government officials called the exercises “routine training,” but Chinese state media, quoting academics, strongly criticized the drills as “a military show of force to defy Beijing.”