U.S. National Security Advisor Jake Sullivan told reporters in Beijing on Thursday (August 29) following his visit to China that the U.S. is concerned about China's actions against the Philippine's 'lawful' maritime practices in the South China Sea and they had a 'vigorous give and take' on the issue of economic security.

Sullivan met Chinese President Xi Jinping in Beijing on Thursday, wrapping up three days of wide-ranging talks aimed at easing tensions between the two world powers ahead of November's U.S. election.

In the South China Sea, China's vessels have repeatedly clashed with Philippine ships. Washington and Manila are bound by a mutual defense treaty, and the United States has pushed for freedom of navigation in areas of the disputed waters.

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"We have made very clear that our mutual defense treaty applies to public vessels, including Coast Guard vessels that are operating in the South China Sea and in other waters," Sullivan told reporters during a press conference in Beijing.

Chinese officials strongly condemned the deployment of a U.S. intermediate range missile system in the northern Philippines during exercises in April, saying they brought "huge risks of war into the region."

Economic security issues also ranked high on the countries' agenda for talks. Ahead of a deadline for confirming steep new tariff increases on certain Chinese imports, the U.S. official said they had "a vigorous give and take on the issue."

The U.S. administration was expected to announce its final plans this week after President Joe Biden unveiled sharply higher tariffs in May on Chinese goods from electric vehicles to lithium-ion batteries, to shield U.S. firms from Chinese excess production. But U.S. industry has pressured the administration to soften the initial proposals.

And ahead of the November presidential elections, Sullivan said "it's unacceptable for any nation to interfere in the U.S. election and this trip was no different in that regard."

(Production: Alessandro Diviggiano, Xiaoyu Yin)