HANOI - The United States on Monday offered $32.5 million in assistance to Southeast Asian nations, more than half to Vietnam, to boost maritime security, which comes as tension grows with China over rival claims in the South China Sea.

On his first visit to Vietnam as secretary of state, John Kerry denied that the assistance had anything to do with China. He however called for “intensified negotiations and diplomatic initiatives” between China and Japan on resolving differences in the East China Sea.

Kerry said up to $18 million of the funds would go toward strengthening Vietnam’s coastal patrols to help its coastguard react quicker to search and rescue missions, and for disasters. The funding would also be used to buy five “fast” patrol boats for Vietnam’s coastguard in 2014, he added. “This announcement has nothing to do with a recent announcement by any other country,” Kerry told a joint news conference with his Vietnamese counterpart, Pham Binh Minh.

“This is part of a gradual and deliberate expansion that has been planned for some period of time which we have been working on,” he said, adding: “This is really an ongoing policy and not some kind of quickly-conceived reaction” to increased tension.

Still, Kerry said the United States opposed “coercion and aggressive tactics” to advance territorial claims, saying any disputes should be resolved through international institutions. China claims almost the entire oil- and gas-rich South China Sea, overlapping in different places with claims made by Taiwan, Malaysia, Brunei, the Philippines and Vietnam.

Meanwhile, state-run media said Monday that a US warship that was forced to manoeuvre to avoid a collision with a Chinese naval vessel had “posed a threat”, after Washington accused China of being the aggressor.

The Global Times newspaper, which often takes a nationalistic stance, said the USS Cowpens guided missile cruiser had “come to China’s threshold and posed a threat to China’s military security”.

Meanwhile, Japan called on China Monday to see “reality” and “accept” there are widespread international concerns over Beijing’s controversial air defence zone.

The comment by Prime Minister Shinzo Abe’s right-hand man came after China singled out Japan for criticism when 11 Asian countries stressed the importance of freedom of overflight at a summit in Tokyo, in a move seen as targeting Beijing.

“We think China should see the reality that many countries in the international community share concerns about the Air Defence Identification Zone and seriously accept it,” Chief Cabinet Secretary Yoshihide Suga told a regular briefing.

A joint statement by Japan and leaders of the Association of Southeast Asian Nations (ASEAN), “agreed to enhance cooperation in ensuring freedom of overflight and civil aviation safety”.

While the statement did not name China, it was seen as a clear rebuke for Beijing, which has sovereignty disputes with Japan and with four members of the economic bloc, and which has been repeatedly accused of intimidation and coercion.