When Chinese fighter jets violated neighboring Taiwan’s airspace by crossing for the first time in decades the “median line” separating the two countries on March 31, the move immediately raised speculation about how the island nation’s American ally might respond.
The provocation came after Chinese President Xi Jinping declared earlier this year that Taiwan’s incorporation into Greater China is “inevitable” and that he will “make no promise to give up the use of force and reserve the option of all necessary means.”
The maneuver marks China’s latest escalation in the South China Sea, a contested maritime area the United States has vowed to keep open and free for international navigation.
A series of tit-for-tat provocations at sea and in the skies hint at a coming confrontation in the area that could bring the US and China into armed conflict and send security shock waves across the wider region.
China’s moves have not been confined to Taiwan, which Beijing deems a renegade province. China has also recently deployed an armada of para-military forces in the form of fishing and other boats which in their hundreds are laying siege to the Philippine-occupied Thitu Island.
The siege comes in apparent response to Manila’s efforts to upgrade a runway and other modest military facilities on the island, which is proximal to the Scarborough Shoal China has occupied since a 2012 naval standoff with the Philippines.
The US failed to respond to that incident, but is now pushing back against China’s militarization of the sea with renewed purpose. For the first time in years, the US deployed on March 25 some of its biggest and most advanced Coast Guard cutters, including the USCGC Bertholf, through the narrow Taiwan Straits separating China and Taiwan.
That follows on Washington’s deployment of the guided-missile destroyer USS McCampbell and USNS Walter S Diehl in January. A month later the USS Stethem destroyer and USNS Cesar Chavez ammunition and cargo vessel were sent through the same waterway for what were officially termed “routine” transits.
The deployments have been backed with a refocused, if not confrontational diplomacy, an apparent answer to previous perceptions US President Donald Trump’s administration was overlooking the region and China’s rising assertiveness in the South China Sea.
During a late February tour of Southeast Asia, US Secretary of State Mike Pompeo assured the Philippines that Washington would come to its rescue in the event of a conflict in the South China Sea, including vis-à-vis China.
“As the South China Sea is part of the Pacific, any armed attack on any Philippine forces, aircraft, or public vessels in the South China Sea will trigger mutual defense obligations under Article 4 of our  Mutual Defense Treaty,” America’s top diplomat said in a press conference in Manila.
“We have your back,” Pompeo reportedly told Filipino leaders, a welcome message to many in Manila after the US failed to respond to its 2012 Scarborough Shoal showdown with China. Manila had recently moved to review the two sides’ defense treaty due to concerns about the US’ commitment to the pact.
America’s reaffirmed backing could include new arms sales. During a visit to the US this month, Philippine Defense Secretary Delfin Lorenzana discussed purchasing America’s High Mobility Artillery Rocket System, with a clear eye on deterring China’s activities in the South China Sea.
In that same direction, the US Navy’s amphibious assault ship USS Wasp recently arrived in the Philippines for a major annual exercise carrying a US Marine Corps contingent that included at least 10 F-35B Joint Strike Fighters. Reports said the deployment could help to lay the groundwork for a future operating concept that could turn amphibious assault ships into light carriers.
One stumbling block in the Philippine-US alliance, however, is President Rodrigo Duterte’s persistent refusal to allow US forces to pre-position weapons at key bases pointed towards the South China Sea, including the pivotal Bautista Airbase on the island of Palawan.
Still, the US is signaling to regional allies a new willingness to counter China’s expanding claims and militarization of features it occupies in the waterway, a policy shift that is putting the region on a new strategic edge.
Last month, the US deployed for the first time in history two pairs of nuclear-capable bombers within a week to the South China Sea. On March 4, the Pentagon also deployed a B-52 bomber over the maritime area, while another participated in a joint military exercise with Japan’s Air Self-Defense Force in the adjacent East China Sea.
A week later, on March 13, two B-52H Stratofortress heavy bombers left Andersen Air Force Base in Guam for ostensibly routine aerial operations in the South China Sea. Each bomber has a weapons payload of over 70,000 pounds.
“US aircraft regularly operate in the South China Sea in support of allies, partners, and a free and open Indo-Pacific,” the US Pacific Command said in a statement after its second overflight operations.
While the ostensible aim of the operations is to ensure freedom of overflight above one of the world’s most crucial waterways, there is more at play, including concerns China aims and is close to imposing an Air Defense Identification Zone (ADIZ).
With Beijing rapidly militarizes its artificially created islands in the South China Sea, security experts believe that it’s only a matter of time before China establishes an exclusion zone in the area and coercively drives out other smaller claimant states through its superior air and naval capabilities.
America’s countervailing overflight operations have gone hand-in-hand with more frequent and aggressive freedom of navigation operations. The US Navy now regularly deploys, often two at the same time, warships to the vicinity of China’s occupied islands in the South China Sea.
In February, Admiral John Richardson, chief of US naval operations, also highlighted the Trump administration’s pushback against China’s “grey zone” or “short of conflict” operations in contested maritime spaces.
The US has recently and openly accused China of deceptively using ostensibly civilian though well-armed and coordinated para-military and fishing vessels as a camouflage for full-fledged military operations, surveillance and territorial expansion in the area.
The Pentagon has recently said that it will now treat China’s People’s Armed Forces Maritime Militia (PAFMM) and other paramilitary Chinese forces as de facto military vessels, meaning US warships will apply the same rules of engagement to PAFMM vessels as it does with the People Liberation Army Navy.
With the US military expanding its operations in China’s adjacent waters, some hardliners in Beijing are calling for a tougher response, including during the recently concluded Boao Forum in Hainan.
Wu Shicun, head of the prominent National Institute for South China Sea Studies in Hainan, called on Beijing to reinforce “deterrence facilities” in disputed areas because “we must deploy some defensive facilities that are able to overawe American warships entering [our] nearby waters.”
“The Americans feel that they alone are not enough,” Wu reportedly said at the forum. “They might also bring in allies such as Britain, Australia or Japan for exercises, or even create a regular joint action regime,” he added.
Whether China truly thinks it senses US weakness is debatable. But with certain US military planners suggesting the South China Sea will be lost to China if current militarization and expansion trends hold, the potential for a region-rumbling seismic showdown is clearly rising.