Though Japan has signed aid pacts in order to win support from ASEAN countries in its dispute with China, Japanese Prime Minister Shinzo Abe's "checkbook diplomacy" may fail because his provocative political actions put the region into a difficult situation, observers said.

On Sunday, Abe concluded a three-day Japan-ASEAN summit in Tokyo during which Japan, in what experts called "an unusual gesture", offered to provide 2 trillion yen ($19.2 billion) in aid for the 10-member bloc.

Japan also pledged fresh aid worth about $610 million in loans to Myanmar, mainly to help the Southeast Asian country's infrastructure projects.

Despite Japan's generous aid package, many of Tokyo's suggestions targeting China were not included in the joint statement released on Saturday, due to opposition by ASEAN, Kyodo News Agency said.

"The word 'threat', in alluding to China's actions in the South China Sea, was not written into the statement, because senior officials from Myanmar, Laos and Cambodia disagreed with the expression suggested by Japan at a pre-summit meeting on Thursday in Tokyo," the Japanese agency reported.

The phrase "freedom of overflight" in the statement was changed from "freedom of overflight over the high seas" in the draft because the Southeast Asian side indicated that "the words 'over the high seas' could be taken as a specific measure focusing on China's air defense identification zone", Kyodo reported.

The statement, which said that the two sides promise to cooperate to ensure "freedom of overflight and aviation safety in accordance with universally recognized principles of international law", is more like a meaningless diplomatic expression, which will not play a substantive influence in regional cooperation, said Yang Xiyu, an expert on international relations studies at the China Institute of International Studies.

"It seems like the statement somehow satisfied Japan's requirement, but it doesn't have any practical meaning. ASEAN didn't play the game of taking sides as Japan wished."

Abe said at a news conference on Saturday that China's recent announcement of the air-defense identification zone over the East China Sea is "unjustly violating freedom of aviation over the high seas" and demanded Beijing rescind it.

During a meeting with Indonesian President Susilo Bambang Yudhoyono, Abe explained Japan's stance on China's air defense zone, which covers the disputed Diaoyu Islands, but Yudhoyono did not give a definite answer as Abe had hoped.

"When the border negotiations are still ongoing, having an open line of communication is crucial to avoid miscalculation that may occur in and around the disputed area," Yudhoyono was quoted by Xinhua News Agency as saying, without naming a specific location.

Yudhoyono said, "It is important that Japan's larger security role is pursued gradually, in a transparent manner and in ways that would strengthen international security, regional order and enhance confidence building."

Foreign Ministry spokesman Hong Lei expressed China's anger over Abe's "malicious slander" of China in the international arena.

"As a defensive measure to safeguard national air security, the establishment of the East China Sea ADIZ is in line with international law and practice," Hong said on Saturday, stressing that it does not affect aviation freedom.

Wang Ping, a researcher at the Institute of Japanese Studies, Chinese Academy of Social Sciences, said Abe's Southeast Asian strategy of isolating China is stupid.

"China has become ASEAN's largest trading partner and the biggest export market since 2011. The free trade zone between ASEAN and China is a good example for regional cooperation. There is no way that Japan can easily buy ASEAN," she said.

"Abe forcing ASEAN to take sides in the disputes between Japan and China is apparently irresponsible," she said.

Liu Jiangyong, an expert on Japanese studies at Tsinghua University, said Japan should be clear that the world expects Japan to handle its relations with China well, rather than building alliances against China.

"Japan originally hoped ASEAN countries would make a joint statement over issues like 'freedom of overflight', then use China's ADIZ as one case to criticize China. ASEAN countries were crystal clear about Japan's intensions," Liu said.

Abe seems to like to push all visiting leaders in Japan to underwrite his ideas against China, he said.