Demonstrators in Vietnam have staged rare protests against China in a long-running dispute over who owns parts of the South China Sea.
In Hanoi, scores of people marched from the opera house towards the Chinese embassy. There were banners laying claim to groups of islands, and criticising China.
There was a similar but smaller turnout in Ho Chi Minh City.
Authorities in Beijing want Vietnam to halt unilateral oil exploration in the disputed waters and to stop harassing Chinese fishing boats.
China is in dispute with several countries over maritime territory.
Police moved in quickly to break up the protests. Vietnam’s communist leaders fear that popular anger against Beijing could rebound against them.
Around 20 people were arrested in Hanoi and driven away by bus.