The most recent of his near daily outbursts came during a series of speeches given in Manila. Duterte announced "I will break up with America"
in response to an alleged refusal by Washington to not sell weaponry to the Philippines. Russia and China, Duterte continued, had both offered to provide weaponry should the Philippines request it.
Duterte's stock with the US government cannot fall much further. Immediately after coming to power Duterte launched a wave of extrajudicial killings
in pursuit of his self-proclaimed war on drug dealers and addicts. Amid the international condemnation for these killings, Duterte has likened himself to Hitler and indicating he would happily kill more. Duterte has insulted the US Ambassador to Manila Philip Goldberg, calling him a "gay son of a bitch,"
and has directed vulgar language at President Barack Obama and said that he can "go to hell."
Despite the reassurance from White House press secretary Josh Earnest that the US-Philippines alliance remains strong, Duterte's continued extreme actions and language pose a real and growing risk to the alliance.
Even as it stands at the moment, serious questions need to be asked of the reliability of the Philippines both as an alliance partner and as a partner in the promotion of the values of democracy and good governance that the US seeks to defend in the region. The real danger, however, is if Duterte makes good on his threat to move toward Moscow or Beijing. Were this to happen, the US security posture in East Asia would be dangerously weakened.
A Philippines falling within the orbit of Beijing or Moscow would undermine the US's ability to defend freedom of navigation in the South China Sea. At the moment, the US and the Philippines undertake joint patrols in the region, and as recently as April 2016, before Duterte's assumption of the presidency, had signed an enhanced alliance agreement that saw the basing of US aircraft at Clark Air Base, joint training exercises and the release of US funding to support military infrastructure enhancements. Duterte has indicated he wishes to review all these agreements.
Duterte's move away from the US would also embolden China. On July 12, less than two weeks after Duterte came to power, the Permanent Court of Arbitration released a damning verdict on Chinese claims in the South China Sea in support of a Filipino submission, sweeping aside all of China's justifications for its occupation of, and in other cases creation of, the small atolls that dot the South China Sea in disregard of the claims of others.
Yet Duterte seems almost completely disinterested in this victory, more concerned with using China as a way to avoid isolation whilst he insults the US than as a threat to Filipino interests. A Philippines unwilling to pursue its claims in the region, claims that support the US position, is a Philippines working to the advantage not of its supposed ally but of its ally's most significant competitor.
We can sketch two futures for the US-Filipino relationship depending on the outcome of the US election.
Duterte, a crude populist, parallels Republican nominee Donald Trump. Yet despite these similarities, a Trump presidency would likely worsen, and worsen rapidly, the prospects of continued US-Filipino cooperation. We can be confident that Trump would not respond with the cool detachment of Obama to a tirade of slurs thrown in his direction, especially given Trump's skepticism of the value of existing alliances which he perceives as not working in the US interest.
Two hot-heads are not good news for stable diplomatic relations, and it is unlikely that Trump would accept that the strategic benefit of a long-term close relationship between Washington and Manila outweigh the short-term costs of Duterte's diplomatic affronts.
Democratic nominee Hillary Clinton would provide a far more traditional take on the US-Filipino relationship. Her victory would likely see a continued effort from Washington to emphasize, as Obama has, the long-term alignment of shared interests and the deep and warm relationship between the two countries that go beyond the personalities in power.
Clinton may be seen as more hawkish than Obama, but she is also a seasoned diplomat who can take insults in her stride in pursuit of a longer term vision. With her eyes set on China, Clinton will be far more concerned with maintaining the US position as it currently stands; a series of close security relationships with the states along China's coastline.
It remains unclear whether Duterte will follow through on his threats, and so his ultimate foreign policy agenda remains unclear. A Duterte of hot temper but little action will be an irritation to the US position, whilst a Duterte who matches words with actions will be a far greater danger and American policy towards the Philippines should work toward preventing the latter whilst accepting the former.