Beijing injected an extra irritant into its long-running dispute with its neighbors with the South China Sea as it announced its annual ban on fishing in the area and vowed to stop vessels that drop a line into the contested waters.
China's move brought a condemnation from Vietnamese fishermen on Monday, as their representative said the move is illegal and threatens their livelihood.
"They can apply the ban in their water, not in our water because that would violate our law," said Nguyen Viet Thang, chairman of Vietnamese Fishery Association.
"We have said before that the ban does not have any validity to Vietnamese fishermen," he told RFA's Vietnamese Service.
While China has imposed similar bans each year since 1999, this year's ban comes at a particularly sensitive time as Beijing has been building islands and asserting itself in the area in an attempt to control much of the critical seaway.
Beijing's previous moves in the South China Sea have sparked anti-Chinese protests in Vietnam.
An oil rig China moves into the area in 2014 triggered anti-Chinese riots and the worst diplomatic crisis between the two neighbors in decades. Vietnam also accuses the Chinese of ramming and sinking Vietnamese fishing boats in disputed waters in 2014 and 2015.
The South China Sea is becoming flashpoint beyond the Vietnamese coast as China and other countries in the region seek control of trade routes, fishing grounds and mineral deposits that lie in the seaway.
China has hauled massive amounts of sand and other material to build up reefs and other features so that it can use the islands. The country has constructed landing strips that can handle military aircraft and added antiaircraft on some of the contested islands.
Taiwan and China both claim nearly the entire South China Sea. Vietnam and the Philippines also have large claims, while Brunei and Malaysia have smaller stakes to waters and features that lie much closer to those nations than they do to faraway China.
On Monday Thang appealed to Hanoi to protect the country's fishermen.
"We asked the government's agencies to be present to protect our fishermen," he said. "They have to be present all the time to protect our fishermen who work legally in our water."
China's unilateral fishing ban in the South China Sea runs from May 16 to Aug 1, according to Xinhua News Agency.
The ban covers a large swath of the water including the Paracel Islands, part of the Gulf of Tonkin and Scarborough Shoal.
Chinese officials said they plan to step up enforcement of their fishing regulations as Zhao Xingwu, head of the Bureau of Fisheries under the Ministry of Agriculture, told the China Daily that the coast guard and local fisheries bureaus will enforce the ban.
"We will definitely step up law enforcement in the South China Sea to enhance regulation of our fishing vessels," he said. "We will also step up the regulation of foreign ships."
One Vietnamese fisherman from Ly Son island of Quang Ngai province told RFA that he knew nothing about the ban, and was preparing to go to sea.
"We can't do anything about the ban," he said. "Fishing is our life. I have to go to make money to support my wife and children. The government can't give us food, and this is how we make our living."
Copyright (copyright) 1998-2016, RFA. Used with the permission of Radio Free Asia, 2025 M St. NW, Suite 300, Washington DC 20036