Vietnamese Prime Minister Nguyen Tan Dung said his government was considering various "defense options" against China, including legal action, following the deployment of a Chinese oil rig to disputed waters in the South China Sea.
Dung's comments, given in a written response to questions from Reuters, are the first time he has suggested Vietnam would take legal measures, a threat likely to infuriate Beijing.
"Vietnam is considering various defense options, including legal actions in accordance with international law," Dung said in an email sent while on a visit to Manila late on Wednesday. He did not elaborate on the other options being considered.
In late March, the Philippines submitted a case to an arbitration tribunal in The Hague, challenging China's claims to the South China Sea. It was the first time Beijing had been subjected to international legal scrutiny over the waters.