Vietnam has delivered a sharp rebuke to China over military drills in the South China Sea, the second such warning in a week as tensions rise between the countries over the disputed waterway.China and Vietnam have long traded barbs over the strategic and resource-rich South China Sea, which Beijing claims most of.Tensions have flared in recent months, with Vietnam suspending an oil exploration project operated by Spain's Repsol in an area off its coast claimed by Beijing.In June, a meeti