VIENTIANE, Laos — The Philippines and Vietnam jointly tabled a draft maritime code of conduct for the South China Sea at the opening of the Association of Southeast Asian Nations summit on Tuesday, an unusually direct procedural challenge to Beijing that organizers said reflected mounting frustration in Manila and Hanoi over what both capitals describe as a year of intensifying Chinese coast guard activity in disputed waters.

The eight-page text, circulated to the ten member delegations shortly before the leaders’ retreat at the National Convention Centre, would replace the long-stalled framework that ASEAN and China have negotiated since 2017 with a binding instrument that includes named choke points, written rules on water-cannon use and harassment of fishing vessels, and a standing dispute-resolution panel under the bloc’s secretariat in Jakarta. A copy of the draft, shared with reporters by a Philippine official on condition that specific language not be quoted verbatim, would also require advance notification of military exercises within 30 nautical miles of features claimed by more than one party.

“The cost of ambiguity has been counted in lost boats, drenched crews and shrinking fish catches,” Philippine Foreign Secretary Enrique Manalo said in opening remarks. “Southeast Asia cannot wait another decade for a text that does not name the seas it claims to govern.”

Vietnamese Deputy Prime Minister and Foreign Minister Bui Thanh Son, who appeared with Manalo at a brief joint statement before the morning plenary, said the proposal was “an offer to the region, not an instrument against any single party,” and noted that Hanoi had shared earlier versions with Beijing through diplomatic channels in late April. Chinese Foreign Ministry spokesperson Lin Jian, asked about the draft at a regular briefing in Beijing on Tuesday, said China had “noted the reports” and would respond through “appropriate channels,” language Asian diplomats read as a placeholder while Beijing assessed the unusually public framing.

The Vientiane summit, chaired this year by Laotian Prime Minister Sonexay Siphandone, is the first ASEAN heads-of-government meeting since the Iran-Israel ceasefire took effect April 15, and several delegations had signaled before arriving that they wanted to use the gathering to reassert a regional agenda obscured by six weeks of Gulf war. A joint statement issued by ASEAN foreign ministers in Jakarta in mid-April had warned that the war’s reverberations risked “displacing the bloc’s own deliberations,” language that Indonesian officials said was meant to nudge consensus toward harder positions in Vientiane.

The draft’s appearance on the first day, rather than being held back for a possible compromise on the third, surprised several delegations. Two Southeast Asian diplomats, speaking on condition of anonymity to describe internal consultations, said Cambodia and Laos had urged a slower process, while Singapore and Malaysia had quietly supported the Philippine-Vietnamese move. Indonesia, which had taken the lead on the April statement, was described as “constructively neutral” — willing to allow the text to be discussed but unwilling to co-sponsor it ahead of consultations with Beijing.

“This is not the way ASEAN traditionally works, and that is precisely the point,” said Bilahari Kausikan, a former Singaporean diplomat and longtime commentator on the bloc’s deliberations. “Manila and Hanoi have decided that consensus, on its own, has become a veto. They are testing whether the rest of the bloc will tolerate a coalition of the willing inside the tent.”

Manila’s push reflects a sharper political climate at home. The administration of President Ferdinand Marcos Jr. has faced sustained criticism since a series of incidents in March and April in which Philippine fishing vessels and coast guard ships reported being blocked, rammed or sprayed with water cannons near Scarborough Shoal and Second Thomas Shoal. The Philippine Coast Guard said in a statement Monday that it had documented 47 such incidents since the start of the year, a roughly 40 percent increase on the same period in 2025. Beijing disputes the count and has accused Philippine vessels of repeated incursions into what it calls Chinese sovereign waters.

Vietnam’s calculations are more diversified. Hanoi’s energy plans depend in part on undisturbed access to gas blocks in waters Beijing also claims, and Vietnamese officials have grown increasingly impatient with what they describe as a creeping Chinese coast guard presence around Vanguard Bank. The Vietnamese delegation pointedly included representatives of state oil company PetroVietnam at one of Tuesday’s working-level briefings.

The proposal lands at a moment when ASEAN’s external relationships are also in flux. Japan, South Korea and Australia — none of them members of the bloc but all dialogue partners — finalized an energy security compact with several Southeast Asian buyers in Tokyo in late April, an arrangement that several diplomats said had subtly emboldened Manila and Hanoi by widening the network of partners they could call on if pressure from Beijing intensified. U.S. Secretary of State Marco Rubio is expected to attend the summit’s dialogue partner sessions on Thursday and was briefed on the draft text before traveling, according to two State Department officials.

“The Marcos government and the Vietnamese politburo have read the room,” said Le Hong Hiep, a senior fellow at Singapore’s ISEAS-Yusof Ishak Institute. “Washington is back to looking east, Tokyo and Seoul have signed binding energy texts, and Beijing has spent a quarter explaining itself in Tehran. That is the window.”

China’s response, while measured in tone, is expected to harden as the summit progresses. A senior Chinese diplomat, briefing reporters in Beijing on background, said the draft was “not a serious basis for negotiation” and warned that any attempt to circumvent the existing framework agreed in principle between ASEAN and China would set back the talks “by years.” Chinese state media outlets, including the Global Times and China Daily, ran commentaries Tuesday accusing the Philippines of acting as a “proxy for extra-regional forces.”

The summit is scheduled to issue a chair’s statement on Thursday, and the question of whether the Philippine-Vietnamese draft is acknowledged in that text — and in what language — is expected to dominate the next 48 hours of corridor diplomacy. Officials said Sonexay’s office had begun consultations on draft language Tuesday evening, and that an ASEAN-China meeting at the senior officials level had been pencilled in for early June to formally receive the proposal.

Diplomats arriving for the evening session said they expected the most consequential exchanges to take place outside the plenary, in bilateral pull-asides between the Philippine and Indonesian delegations and between Vietnam and Malaysia. A Filipino official, asked whether Manila expected the draft to be adopted at this summit, smiled and said the goal for the week was simpler. “We want it on the table,” the official said. “After that, the table belongs to everyone.”