HANOI — Taking clear aim at China’s growing aggressiveness in territorial disputes with its smaller neighbors, Secretary of State John F. Kerry announced Monday that the United States will boost maritime security assistance to the countries of Southeast Asia amid rising tensions with Beijing.
On his first visit to Vietnam as America’s top diplomat, Kerry pledged an additional $32.5 million for members of the Association of Southeast Asian Nations to protect their territorial waters and navigational freedom in the South China Sea, where four states have competing claims with China.
Included in the new aid is up to $18 million for Vietnam alone that will include five fast patrol-boats for its Coast Guard. With the new contribution, US maritime security assistance to the region will exceed $156 million over the next two years, he said.
Kerry said the new assistance was not a ‘‘quickly conceived reaction to any events in the region’’ but rather a ‘‘gradual and deliberate expansion’’ of US support as part of the Obama administration’s broader decision to refocus attention on the Asia-Pacific region. However, his comments came as Washington and Beijing trade barbs over a near collision between US and Chinese naval vessels in the South China Sea 11 days ago.
China announced in late November that it was establishing a defense zone over the East China Sea, a maritime area between China, Taiwan, South Korea, and Japan.
All aircraft entering the zone must notify Chinese authorities beforehand, and China would take unspecified defensive measures against those that don’t comply. Neighboring countries and the United States have said they will not honor the new zone — believed aimed at claiming disputed territory — and have said it unnecessarily raises tensions.
Already, China has claimed it has a sovereign right to establish a similar zone over the South China Sea, where China and the Philippines are locked in another long-running territorial dispute.
‘‘Peace and stability in the South China Sea is a top priority for us and for countries in the region,’’ Kerry told reporters at a news conference with Vietnam’s foreign minister, Pham Binh Minh. ‘‘We are very concerned by and strongly opposed to coercive and aggressive tactics to advance territorial claims.’’
While stressing US neutrality on the competing sovereignty claims, Kerry called on China and the Association of Southeast Asian Nations to quickly agree to a binding code of conduct for the South China Sea and to resolve their disputes peacefully through negotiations.
China’s increasing assertiveness in the region — including the establishment of the East China Sea air defense zone — has alarmed many of the 10 members of the Association of Southeast Asian Nations, including Vietnam and the Philippines, which Kerry will visit Tuesday.
In addition, Kerry made clear that the aid is designed to help Southeast Asian nations defend their waters from encroachment and his announcement was accompanied by blunt criticism of China for its creation of a new air defense zone and suggestions that it might do the same in the South China Sea.
As such, it is almost certain to anger Beijing, which bristles at what it sees as US interference in areas China considers to be in its ‘‘core interest.’’
China and Vietnam fought a bloody border war in 1979, and in 1988 a naval battle close to disputed islands in the seas left 70 Vietnamese sailors dead. Disputes over fishing rights in the region have triggered occasional violent incidents and hiked up diplomatic tensions since then.
Kerry had harsh words for China’s new East China Sea air defense zone, saying it ‘‘clearly increases the risk of a dangerous miscalculation or an accident’’ that could lead to possible conflict between China and Japan over a string of small islands that each claim as its own.
The United States is ‘‘very concerned about recent actions that have increased tensions between China and Japan and we call for intensified negotiations and diplomatic initiatives.
‘‘The zone should not be implemented, and China should refrain from taking similar unilateral actions elsewhere, particularly in the South China Sea,’’ Kerry said, reiterating that such moves by Beijing would not affect US military operations in the region.
Beijing regards the entire South China Sea and island groups within it as its own and interprets international law as giving it the right to police foreign naval activity there. The Chinese navy is operating with increasing frequency in the South China Sea and around Japan as part of China’s development of its blue water navy.
Tensions were highlighted earlier this month when a Chinese warship nearly collided with an American cruiser in the South China Sea.