Prime Minister Shinzo Abe's three-day official trip to China through Saturday put priority on conjuring up images of friendliness, despite persistent differences over security and territorial issues.

Leading up to talks with Chinese President Xi Jinping and Premier Li Keqiang in Beijing, Abe had been discreetly omitting the word "strategy" in public speeches when referring to his pet concept of a "free and open Indo-Pacific," in consideration of China, which has regarded it as having hostile connotation, according to Japanese government sources.

The concept, put forth by Abe in 2016, involves Japan's intention to boost relations with countries from Asia to as far as Africa that share such universal values as democracy and the rule of law, in an indirect counter to China's growing clout in the vast region.

"There's no need to say 'strategy.' It's enough to say 'Indo-Pacific,'" Abe told people close to him in late September, in a sign he wanted to alleviate any distrust that Xi, the most powerful Chinese leader in years, would have toward him, the sources said.

On Oct. 12, he said in an interview with Hong Kong's Phoenix TV, "From the standpoint of a free and open 'Indo-Pacific,' Japan can cooperate with China, which promotes the 'One Belt, One Road'" initiative for the development of infrastructure and trade across Asia, Europe and Africa.

During his trip to Europe in mid-October, Abe also referred to the importance of advocating a "free and open Indo-Pacific" but avoided calling it a strategy.

Leaving out the word marked a change from his previous stance.

Around April, Chinese State Councillor and Foreign Minister Wang Yi told a governmental meeting in Beijing following a trip to Japan that the "Indo-Pacific strategy" should not be mentioned when discussing cooperation between the two countries, and his request was unofficially conveyed later to the Japanese side, ahead of the Chinese premier's visit to Tokyo in May.

Using several channels, Japanese officials told China that the strategy is not in conflict with Xi's signature initiative of connecting countries along the ancient Silk Road trade routes more closely and expressed Tokyo's readiness to cooperate on the project.

When Li came to Japan, Abe told him that Japan-China relations have entered an era of "cooperation from competition," an expression Abe repeated while he was in Beijing.

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He even accompanied Li on a trip to Hokkaido in northern Japan and saw him off at New Chitose Airport near Sapporo and the premier's visit ended in a friendly atmosphere.

Abe apparently judged afterward he does not have to worry about using the term "Indo-Pacific strategy."

On June 21, Abe told Adm. Philip Davidson, head of the U.S. Indo-Pacific Command, at his office in Tokyo that he wants to "advance the Indo-Pacific strategy with the United States."

On July 17, at a joint press conference with European Council President Donald Tusk in Tokyo, he also said, "I want to strengthen the alliance (with the European Union) under the Indo-Pacific strategy."

But as Abe's visit to Beijing drew close, the Chinese side again communicated to the Japanese government about its dissatisfaction with usage of the concept, according to the sources.

A senior Chinese official told an official close to Abe in September to take concrete action to address Beijing's concern, according to a source close to bilateral ties.

Abe decided not to use the concept apparently just before or after Japan's national security adviser Shotaro Yachi met with Chinese Politburo member Yang Jiechi on Sept. 25.

In his policy speech on the opening day of parliament's extraordinary session on Wednesday, Abe only said, "I want to build peace and prosperity in the vast region from the Asia-Pacific to the Indian Ocean," although in January in his address to the Diet he used the wording.

Nevertheless, it is believed that Abe will not abandon the strategy anytime soon and will continue to seek the enhancement of ties with a number of countries in the Indo-Pacific region, with a source at the prime minister's office saying it is an "open secret" that the concept includes an intention to counter China.

The origin of the strategy may be traced to Abe's proposal of "Asia's Democratic Security Diamond" that came days after he returned to power for the second time in December 2012.

The idea was to protect the stability of the region and the sovereignty of the Japan-controlled, China-claimed Senkaku Islands through more security cooperation with Australia, India and the United States.

The vision is also reflected in the National Security Strategy that was endorsed by the Cabinet in December 2013 and which is effective until today.