Vietnam offers explicit backing for United States intervention in the region, while the president of the Philippines tours China and announces his “separation” from the US.
The contrasting statements underline the extreme fluidity of international relations in Southeast Asia, and the difficulty of sustaining a united front against China’s territorial ambitions.
Vietnam has calculated that closer ties with Washington, against the backdrop of President Obama’s “pivot to Asia”, will help it resist China’s growing belligerence in the South China Sea.
But US efforts to bolster the position of its allies and partners in the disputed waters could be fatally undermined by President Duterte’s apparent intention to do a separate deal with China and abandon its alliance with the United States.
Mr Duterte is courting massive financial assistance from China. In return he seems to be contemplating bilateral concessions to China in the South China Sea, and has threatened to expel US forces from the Philippines.
Seeing the danger, Vietnam’s defence ministry said it was prepared to support US military intervention if it helped keep “peace and stability”.
Such a statement, from the defence ministry of a country that fought such a long and bloody war against American “imperialism”, indicates how far Hanoi has travelled in its efforts to resist Chinese pressure.
The comments were made during a meeting between the vice-defence minister, Senior Lieutenant-General Nguyen Chi Vinh, and Cara Abercrombie, the Pentagon official responsible for South and Southeast Asia.
Ms Abercrombie said that the US would not change its re-balance strategy, which puts renewed emphasis on Washington’s military presence in the western Pacific, and seeks to bolster allies and partners.
The US lifted its arms embargo on Vietnam in May, and two US naval vessels paid a visit to Vietnam’s port facilities at Cam Ranh Bay this month, for the first time since the Vietnam War.
President Duterte’s overtures to China and his overt hostility to the United States have sparked concern across a region that feels threatened by the rising military power of China.
The Philippines has provided a strategic base, and offered moral authority, to the United States, as it seeks to resist China’s claim to international waters and disputed territories in the South China Sea.
The former Philippine foreign minister, Albert del Rosario, was quoted as expressing alarm at his country’s new direction.
“There appeared to be a lack of clarity from the incumbent administration on what a principled and independent foreign policy should be,” he said in comments quoted by the GMA news service.
“This is most difficult to comprehend since the perceived favoured state has clearly and consistently exhibited, and continues to demonstrate assertive behaviour while blatantly violating international law to the grave disadvantage of the Philippines and to the detriment of our national interest,” he said.
It remains unclear how far President Duterte is prepared to go with his diplomatic realignment.
Vietnam, however, will continue to hedge its bets.
For all the improvements in ties with the US, it has been careful not to break with China despite the heightened military tension between them.
Three Chinese warships will be allowed to dock at Cam Ranh Bay this weekend in what looks like an attempt at confidence building between two wary neighbours.
High level dialogue has also resumed between the two countries’ defence ministries.
The flux in regional diplomacy, and doubts about US policy given the upcoming presidential election, mean that a highly delicate strategic standoff has become even more fraught with uncertainty.