MANILA - President Rodrigo Duterte's next foreign policy move will “critically affect” security in Asia, a former presidential adviser said Saturday, following the Philippine leader's controversial remark about "separating" from the United States.

While in China for a state visit, Duterte announced his "separation" from the United States, saying he will be more dependent on China in the future.

Now that he's set to leave for Japan, his next decisions on foreign policy will greatly influence international relations and security since Tokyo is a very close ally of the US, said former congressman and national security adviser Roilo Golez.

He explained that Japan has been keenly observing China's actions and what is happening in the South China Sea, making Manila a “very vital part of the security situation.”

Like the Philippines, Japan is also caught in its own territorial dispute with China over a group of uninhabited islands in the East China Sea.

“Japan is very sensitive to what China is doing. And the situation here in the Philippines, depending on the next move, will critically affect balance of power here and will have an effect on the security of Japan,” Golez told Nancy Irlanda on Dateline Philippines Weekend.

Japanese Embassy Deputy Chief of Mission Atsushi Ueno also earlier said Japan will seek clarification on Duterte's foreign policy during his state visit to Tokyo.

• READ: Japan seeks clarity on Duterte foreign policy: embassy

Golez he expects Japan to firm up relations with Manila's delegation and to “try to fix things” between the Philippines and the US since the alliance of the two countries is in their interest.

Upon his arrival in Davao on Friday night, Duterte did clarify that he just meant a “separation of foreign policy” when he announced his “separation” from the US.

This clarification is “very reassuring” according to Golez since some analysts see the country’s situation as “rather unstable” following a number of controversial statements the President has made in the past.

“In international relations and security, very important is stability. Even if it’s [a] hostile situation, as long as it’s stable, then people can adjust to that, the policy makers can adjust to that. But right now, the situation is rather unstable as far as some international relations analysts and international security analysts are concerned,” he said.

Golez added that Duterte’s projection of “rebalancing” the country’s foreign policy to make it more independent contradicts his earlier statements in China.

The President's announcement of a China-Philippines-Russia triumvirate also does not show independence, he said.

“He [Duterte] is part of a triumvirate against the world. That does not appear to be independent because being independent means you treat everybody equally,” Golez said.

• READ: Duterte: It's Russia, China, PH 'against the world'

Duterte is scheduled to visit Japan from October 25 to 27.