Vietnam steps up security after deadly riots

Vietnamese security officers set up a fence outside an area of the Chinese Embassy in Hanoi, Vietnam on Sunday, May 18, 2014.

The riots in Vietnam have killed at least two Chinese citizens and injured many more. The violence has threatened to damage international trade and investment in the country.

Vietnamese authorities are finally clamping down such attempts, after protests in the past few days got way out of hand.. damaging Chinese and other foreign businesses, and threatening foreign investment. On Sunday, a heavy police presence restored calm to the streets of the Vietnamese capital. But as far as China is concerned, the damage is already done.

In a written statement, Foreign Ministry spokesman Hong Lei said on Sunday that China has raised its travel warning for Vietnam. China is also suspending part of its bilateral exchange program with the country.

Vietnam says it will prevent any new outbreak of violence. The country's lead police investigator defended the performance of the security forces, dismissing criticisms that authorities were slow to respond.

"The police force was quickly deployed and took tough measures, and we were able to reduce the consequences to the lowest possible level. We have to say that we were in complete control of the situation. We were not being passive and slow to react." Vietnam's lead police investigator Hoang Kong Tu said.

Thousands of anti-China protesters ransacked, looted and set fire to foreign-run factories in southern Vietnam on Tuesday and Wednesday in a wave of violence sparked by a dispute over China's placement of an oil rig in waters claimed by both countries.

Despite strained diplomatic ties at times, trade between China and Vietnam has been robust, standing at 50 billion dollars last year. But that may change, and China called on Vietnam to improve its trade and investment environment on Saturday.

Meanwhile, China's Spring and Autumn Airline said it plans to suspend all charter flights from Shanghai to Vietnam starting from Monday.