HANOI, Vietnam — The United States Monday offered fresh financial assistance to Vietnam to boost maritime security on its borders, which comes as regional tension grows with China over territorial claims in the South China Sea.

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

He repeated that the United States did not recognize a new air defense zone announced by China this month over the East China Sea.

Kerry said the United States would provide up to $18 million to Vietnam to strengthen coastal patrols to help with search and rescue missions and disaster response.

The funding would also be used to buy five "fast" patrol boats for Vietnam's coastguard in 2014, he said.

"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 an ongoing policy and not some kind of quickly conceived reaction."

While announcing closer cooperation between the United States and Vietnam on a range of issues from the economy to education, climate change and trade, Kerry said he had raised U.S. concerns with Minh on Vietnam's human rights record.

Minh acknowledged differences with the United States over human rights.

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.

The United States has said it is neutral in the dispute — centered on China's historic claim of waters deep in the maritime heart of Southeast Asia — but is determined to preserve peace and ensure that sea-lanes vital for the world economy are not hindered.

China also has disputes with Japan and South Korea over different sets of tiny islands.