Japan is keeping a close watch on Chinese President Xi Jinping's attempts to bolster relations with North Korea, as Tokyo continues to grapple with the best way to go about arranging a summit with Pyongyang, diplomatic sources said.

Closer ties between Beijing and Pyongyang could crush the hopes of Japanese Prime Minister Shinzo Abe, who has been trying to pave the way for a meeting with North Korean leader Kim Jong Un in cooperation with the United States.

As Beijing has been eager to use Pyongyang as a bargaining chip to move ahead with trade negotiations with Washington, it is unlikely that China would help Japan -- a close U.S. ally -- realize a summit with North Korea, the sources said.

Abe, who has recently expressed willingness to meet with Kim "without conditions," has been doing his best to deepen personal relations with U.S. President Donald Trump, whose efforts at denuclearization talks with Pyongyang remain stalled.

Xi's surprise two-day visit to North Korea through Friday could encourage Kim to keep his distance from the United States and Japan, which would "further reduce" the chances of a meeting between Abe and Kim, a Japanese government source said.

Abe has emphasized that Tokyo and Washington have been working in tandem to tackle matters related to the Korean Peninsula, including nuclear weapons, ballistic missiles and the past abductions of Japanese nationals by the North's agents.

Trump and Kim, meanwhile, failed to strike a deal at their second summit in the Vietnam capital Hanoi in late February over the gap between Washington's insistence on denuclearization and the amount of sanctions relief demanded by Pyongyang. Since then, their talks have been deadlocked.

In an apparent bid to prod the United States into making concessions in negotiations, North Korea has resumed provocative actions such as firing projectiles that appeared to be short-range ballistic missiles in early May.

Pyongyang has claimed that it has already implemented concrete measures to attain denuclearization and urged Washington to ease economic sanctions, which have taken a toll on North Korea's economy.

With the United States showing little signs of shifting its hard-line stance against North Korea, Abe has started to change his tune, saying early last month, "I myself need to face Chairman Kim without conditions" to resolve several bilateral issues.

The Japanese prime minister had previously suggested a future summit with Kim would not be possible without a guarantee of progress.

Abe may have believed that North Korea really wants the international community to lift economic sanctions and that it would ask for Japan's help as long as its negotiations with the United States remain at a stalemate, the government source said.

In reality, however, North Korea has not leaped at Abe's offer. On the contrary, its state-run media have lambasted Japan's proposal to hold a summit as being "the height of brazen-facedness."

"Abe tenaciously knocks at the door of Pyongyang while making an advertisement as if the Japanese government's policy for negotiation with the DPRK has changed," the Korean Central News Agency quoted a spokesperson for a state agency as saying earlier this month.

"But there is nothing changed in its hostile policy towards the DPRK," the news agency also quoted the spokesperson as saying, using the acronym for North Korea's formal name, the Democratic People's Republic of Korea.

Under such circumstances, China is set to boost its economic and political influence over North Korea. The two countries, which fought together in the 1950-1953 Korean War against U.S.-led United Nations forces, have been long described as "blood brothers."

Although Sino-Japanese ties have improved, it is "almost impossible" for China to support Abe -- a friend of Trump -- in his bid to have a meeting with Kim, as Beijing has been engaged in a tit-for-tat tariff trade war with Washington, one of the diplomatic sources said.

Foreign affairs experts echo the view, with Jeff Kingston, director of Asian Studies at Temple University Japan in Tokyo, saying, "Japan is seen to be a U.S. client state, so it is viewed through that lens in North Korea and China."

"I don't think Beijing will help Tokyo in any substantive way in terms of overall policy" toward North Korea, Kingston added.


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