TOKYO (Kyodo) -- Japanese business leaders expressed concern about the U.S. economy turning more protectionist under Donald Trump after he was reelected president of the world's biggest economy, while also calling for deepening ties between the two countries at a time of geopolitical turmoil.

The sense of caution came as Trump vowed to raise tariffs and lower taxes for domestic businesses in his presidential campaign while also attacking China as an economic threat.

"We hope he implements harmonious policies as the leader of a superpower that supports the world economy and the rules-based free trade system without turning overly protectionist," Ken Kobayashi, chairman of the Japan Chamber of Commerce and Industry, said in a statement.

The partnership between Japan and the United States in the economic and security spheres has remained firm, and the organization expects the two countries to advance the relationship further, Kobayashi said.

Masakazu Tokura, chairman of the Japan Business Federation, said he hopes the Trump administration "will view Japan as a vital partner in the international community, allowing our countries to collaborate with others to rebuild an open international order based on the rule of law."

Citing Trump's close ties with the late former prime minister Shinzo Abe, the head of Japan's biggest business lobby said, "I am confident that he will develop an equally strong relationship with our current prime minister, Shigeru Ishiba" to deepen the bilateral relationship.

Takeshi Niinami, chairman of the Japan Association of Corporate Executives, warned that Japan must prepare itself for unexpected changes in a broad range of issues such as trade and security, saying many countries will be affected after Trump takes office.

Japan should strengthen ties with South Korea over regional security while promoting more interaction with China to revitalize trade and investment between the two countries, he said.