Metro Manila (CNN Philippines) — Former Foreign Affairs Secretary Albert del Rosario is calling on the new administration to count the cost of shifting alliances away from the United States.

"Has anyone in government sat down to calculate the probable loss of economic benefits if we pursue the foreign policy we are now pursuing?" Del Rosario said on Wednesday.

He said the Philippines received over $4 billion in development financing from the US from 2012 to 2015. This year alone, the country will receive $140 million in military assistance from the US -- its only treaty ally. Companies also tap about $800 million in annual trade benefits with the US.

"We will lose that," he said.

The diplomat was speaking during a forum organised by his consultancy group, ADR Institute. The talk focused on the economic priorities of the Duterte administration, but discussions inevitably veered towards the role of foreign policy in luring investments.

President Rodrigo Duterte has threatened to cut ties with the US after it criticized the rising death toll of his war on drugs. He said the Philippines would turn to China for an alliance instead.

After turning down repeated requests for comment throughout the event, Del Rosario finally broke his silence at the close of the program.

"Why is the Philippines distancing itself from [a country] who has worked specifically on promoting the rule of law, which is to the advantage of the Philippines?" he asked.

"Vis-a-vis, why is the Philippines suddenly embracing a country that has been blatantly violating the rule of law to its disadvantage?" he continued, making a thinly veiled reference to China's incursions into the West Philippine Sea.

For his part, ADR Institute President Dindo Manhit said it was a welcome move to rebuild Philippine-Chinese relations after the maritime dispute between the two countries.

But both Manhit and Del Rosario agreed foreign policy need not be a "zero-sum game."

"Instead of drastically changing its friendship from one country to another, the Philippines should maintain its good relations with its trusted friends and pursue constructive relations with all its neighbours," Manhit said.

Del Rosario added: "The Philippines can make new friends without losing its old ones."

Foreign Affairs Secretary Perfecto Yasay earlier told the United Nations General Assembly that the Duterte administration is adopting an "independent foreign policy."

But Del Rosario said the government was getting "driven off-track."

"Our foreign policy is independent when first and foremost is the promotion of our national interest... Such that we stand up for what is right and that we defend what is ours," he said.

Proceeding with caution

The strength of the economy makes the Philippines an attractive destination for investors, but the controversy surrounding the government means they are also proceeding with caution, officials said.

Australian Ambassador to the Philippines Amanda Gorely said Australian companies look for a conducive regulatory environment, skilled workforce and steady economic returns when they invest in a country.

But there is also "something intangible" they want to see: confidence, rooted in political stability, she said in the forum.

"I am often asked about my outlook for the Philippines and I always say, it's still the very early days of the new administration. We need to remain cautiously optimistic."

For her part, Yurika Suzuki, a research fellow at the Japan External Trade Organization, said Japanese businesses appreciate the country's robust fundamentals.

"I just wish it won't be overshadowed by uncertainty in politics and foreign policy," she said.

"We are all cautiously observing what is going on."

Also read: PH, U.S.: We're still friends