MARIKO KODAKI, GAKU SHIMADA and KATSUJI KAMEI, Nikkei staff writers

TOKYO — “Is Shinzo OK?” U.S. President Donald Trump asked the newly minted Prime Minister Yoshihide Suga during their first telephone call on Sunday.

Trump said that he had heard from Suga’s predecessor, Shinzo Abe, that the former chief cabinet secretary was his indispensable right-hand man.

“Call me anytime, 24 hours,” the American president said.

Abe’s ironclad relationship with Trump, a kind of rapport that other world leaders struggled to form with the U.S. leader, was one of the driving forces that made him the longest-serving prime minister in Japanese history.

Suga’s diplomatic debut was relatively easy. All he had to do was to slip into the driver’s seat that Abe had vacated.

Ever since the days of former President Barack Obama, the U.S. has been reluctant to act as “world’s policeman.” Trump is equally unenthusiastic about overseas engagement.

Abe tried to fill this vacuum by deepening ties with the Quadrilateral Security Dialogue, known as the “Quad,” that includes the U.S., India and Australia. Simultaneously, he strengthened the Japan-U.S. alliance by allowing Japan to participate in collective self-defense, expanding the Japanese role in the partnership.

Suga inherits this foreign policy. The fact that Suga also called Australian Prime Minister Scott Morrison on Sunday underscores this path.

The core of the strategy is to prepare for China, whose increasing presence as a military and economic heavyweight in the Indo-Pacific has raised concerns for other nations in the region.

China has infringed into Japan’s territorial waters around the Senkaku Islands in the East China Sea. It is building military hubs in the South China Sea and has two operating aircraft carriers.

“China is already ahead of the United States in certain areas,” the Pentagon wrote in a report to Congress this month.

In terms of military budget, the U.S. still has a threefold lead on China. But Beijing is investing in areas that will allow it to quickly fill that disparity, such as artificial intelligence and new types of missiles.

“The People’s Liberation Army continues to pursue an aggressive modernization plan to achieve a world-class military by the middle of the century. This will undoubtedly embolden the PLA’s provocative behavior in the South and East China seas, and anywhere else the Chinese government has deemed critical to its interest,” U.S. Defense Secretary Mark Esper said last month.

To further develop the U.S.-Japan security alliance, Suga will unveil by year-end steps to improve the nation’s deterrence capability.

Washington’s focus is on whether Japan can come up with truly effective measures, such as a defensive strike option to prevent imminent attacks.

Still, boosting the security partnership with the U.S. alone will not prepare Japan to respond to the changing security environment in the Asia-Pacific region, analysts say.

In addition to encouraging the U.S. to stay engaged with Asia, Japan needs to continue advancing cooperation with Asia-Pacific nations on the economic and other fronts.

Countries in the region have felt the weight of China’s economic influence. Most recently, Beijing moved to limit agricultural imports from Australia after Canberra called for an independent probe into the origin of the new coronavirus, in what critics say is a retaliatory move by China that sends a message to other nations.

Fearful of economic retribution, some emerging economies — particularly in Southeast Asia — have long refrained from criticizing China. Predictions show China’s gross domestic product surpassing that of the U.S. in the 2030s to become the world’s largest economy. If this happens, Beijing could grow impervious to calls from the international community.

To counter this, countries that share common democratic and free-trade values could band together through multilateral frameworks such as the Trans-Pacific Partnership free trade bloc. Coaxing an inward-looking U.S. back into the TPP presents another challenge for Suga.

Additional reporting by Yukio Ishizuka in Tokyo and Tsuyoshi Nagasawa in Washington.