MANILA - The Philippines' incoming ambassador to China voiced optimism Thursday over resolution of the two countries' territorial disputes in the South China Sea, albeit not overnight, citing past cases in which China settled longstanding border disputes with Vietnam and the former Soviet Union through rapprochement and dialogue.

Speaking at the China-Philippines Dialogue 2016 forum in Manila organized by the China Daily, Jose Santiago Sta. Romana, whose appointment is awaiting confirmation, said there are lessons to be learned from the experience of Vietnam and the former Soviet Union in negotiating with China to resolve their respective disputes.

"The basic lesson is, if you use hardball tactics with China, expect the same, or more (from China). So when you say, 'what is ours is ours,' they will say the same thing. And if you don't yield, and if you combine it with just megaphone diplomacy and forcing your way, expect that there'll be a stalemate," said Sta. Romana, a former Beijing bureau chief of ABC News and currently the president of the Philippine Association of Chinese Studies.

The resolution of Beijing's disputes with Hanoi and Moscow, which started by having good political relations with each other and then employing "quiet and high-level summit diplomacy," shows "it's possible to achieve" a settlement with the world's No. 2 economic power, he said.

"They were able to resolve their territorial dispute, but it took time," he said, noting the one with Vietnam took eight years, and 10 years in the case with the Soviet Union.

Sta. Romana said that with the restoration of amicable relations with China under Rodrigo Duterte's presidency, two tracks will be pursued separately -- one for economic cooperation and other non-contentious related issues, and the other for issues related to the South China Sea disputes.

He said Manila will "go full blast" on the first track in the wake of Duterte's productive visit last month to China, where he met with President Xi Jinping and secured Chinese pledges amounting to $24 billion in loans and investment.

"The economic cooperation will be fast-tracked so the Filipino people will garner, will experience the tangible gains from the bilateral relations."

With regard to the territorial disputes, he said, the two sides will firstly "discuss and understand each other's positions," after which the dialogue will proceed "according to the speed of consensus that can be achieved."

"We don't expect the Chinese to change their minds overnight, or through one session. It would take time."

Sta. Romana noted that high-level dialogue has already borne fruit, with the agreement during Duterte's China trip to set up a bilateral consultation mechanism on South China Sea issues.

Duterte's meeting with Xi also resolved the problem of restricted access by Filipino fishermen to disputed Scarborough Shoal, which China has controlled since 2012.

China's naval vessels have withdrawn from the area, though a Chinese coast guard presence continues.

But since that is just an "informal, friendly understanding," Sta. Romana said, there is a need to slowly formalize it, as well as to establish rules of engagement between the coast guards of the two countries.

A landmark ruling in July by a Netherlands-based international tribunal invalidated China's nine-dash line claim over almost the entire South China Sea and judged Scarborough Shoal to be a traditional fishing ground of many nationals, including Filipinos and Chinese.

"The Chinese, of course, still maintains their effective control (of the Scarborough Shoal) because they have a sovereignty claim. But now the Philippine Coast Guard is trying to have a roving presence so that, eventually, we could say we have not given up our sovereignty claim when we resolve it diplomatically," Sta. Romana said.

While he hopes the Chinese to eventually leave the Scarborough Shoal, his "more realistic" view is that "the way out is cooperation between the two sides."

"This is a common heritage of mankind," he said, while pointing to a provision of the U.N. Convention on the Law of the Sea that says countries bordering the same sea should cooperate to manage its resources.

Sta. Romana said that while a resolution of the disputes may not happen during the term of Duterte through 2022, "we'll give it a shot."

==Kyodo