"[China's foreign minister] had asked us to open ourselves for bilateral negotiations but outside, or [in] disregard of, the arbitral ruling," Yasay told the cameras.
"This is something I told him was not consistent with our constitution and our national interest."
The Chinese side did not like that answer, according to Yasay. "They said that if you insist on the ruling and discussing it along those lines, then we might be headed for a confrontation," he said.
Although Beijing has yet to comment on the exchange, they've spent the last seven days making their displeasure and defiance clear.
In the decision issued July 12, the tribunal found there was no legal or historical basis for China's claims to most of the South China Sea. It also found that China violated the Philippines’ sovereign rights by constructing artificial islands. Beijing dismissed the decision as a piece of "trash paper."
The question now is whether China's leaders will double down on their hardball strategy or find a way to take a step back. So far, Beijing has pursued the former — at least publicly.
After days of aggressive editorials, China this week began what it said will become regular military air patrols over he South China Sea.
Xinhua, a party-controlled newswire, said Monday that China's air force "recently" flew an air combat patrol over the Scarborough Shoal, a disputed fishing ground not far from the Philippine coast. Photographs released by the news agency show a Chinese H-6K bomber cruising high above a submerged shoal in azure sea.
China seized controlled of Scarborough Shoal in 2012, and its coast guard has since angered Manila by chasing out Filipino fishermen. The Permanent Court of Arbitration last week ruled that barring Filipinos from the shoal violated "traditional fishing rights."
Filipino television crews on Friday reported that, despite the ruling, China continued to block Filipino fishermen from the area. There has been speculation that China may eventually reclaim land or even build on the feature, a move that many experts see as a "red line" because of its proximity to the Luzon coast.
The air patrol announcement coincided with a meeting between the commander of China's navy, Wu Shengli, and U.S. Chief of Naval Operations Adm. John Richardson, which ended with more stern words from the Chinese.
Although Wu reportedly called for "cooperation" with the U.S., he made it clear that China plans to continue its island-building and would not cease "no matter what country or person applies pressure," according to state media reports. China is also conducting military drills off its southern coast this week.
It is not clear why Yasay decided to go public on a Chinese offer made on the sidelines of an event. In the run-up to the Asia-Europe summit, which took place in Mongolia last week, a senior Chinese diplomat said the Philippines' case would absolutely not be discussed.
"The ASEM leaders' summit is not a suitable place to discuss the South China Sea. There are no plans to discuss it there on the agenda for the meeting. And it should not be put on the agenda," Kong Xuanyou, assistant foreign minister, told the press.
Yasay's comments seem to defy that sentiment, but he insisted there is still room for negotiation. "I really honestly feel that this is something they have to make on a public basis but I also sensed there was room for us to talk very quietly using backdoor channeling" — a very public call for private talks.
Xu Jing contributed reporting from Beijing.