How Will Taiwan Defend a Disappearing Median Line in the Strait?
Source：USMC
The Taiwan Strait, though only 160 kilometers wide, is a crucial passage for one-fifth of global maritime trade. Warships from the U.S., Japan, and Canada frequently traverse the strait to affirm its status as international waters—not a part of China’s territorial sea. The defense of freedom of navigation is not about ideology; it is a matter of necessity.
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How Will Taiwan Defend a Disappearing Median Line in the Strait?
CommonWealth Magazine
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The Taiwan Strait serves as a natural strategic barrier for Taiwan. It is hard to imagine that this narrow stretch of water, which escorts one-fifth of global maritime trade, could also become a safeguard for Taiwan’s security.
Since former U.S. House Speaker Nancy Pelosi’s visit to Taiwan three years ago, China has publicly conducted at least four large-scale military exercises encircling Taiwan. Each time, Beijing has simulated a blockade to cut off U.S. military support from the east.
China has repeatedly declared the Taiwan Strait as its “internal waters,” further eroding the division between the two sides. Last year, Beijing even dispatched coast guard vessels into restricted waters around Taiwan’s Kinmen Islands, enforcing its authority unilaterally.
Taiwan Coast Guard patrols Kinmen waters. (Photo: Pei-Yin Hsieh)
Yet, while China has intensified its “gray zone” tactics to blur the boundaries, Taiwan has quietly expanded its international cooperation, gaining new allies in unexpected ways.
Covert Diplomatic Collaborations Begin to Surface
Last summer, Japanese broadcaster NHK aired exclusive footage of Taiwan’s Coast Guard ship Patrol Vessel No. 9 conducting joint search-and-rescue drills with Japan’s Coast Guard near the Boso Peninsula, south of Chiba Prefecture. The footage clearly showed ship numbers and crew members.
However, NHK’s commentary remained ambiguous: “Japan seems to be engaging in cooperation with neighboring countries.” The Japan-Taiwan Exchange Association declined to comment.
This was not the first Taiwan-Japan coast guard exchange, but it marked the first time such an exercise had been made public since the two sides severed diplomatic ties. The timing was significant—just after Taiwan’s Coast Guard had been forced to confront China’s “second navy,” the China Coast Guard, which had begun regular patrols in Kinmen’s waters.
There were other surprises.
Last year, U.S. Coast Guard Captain Rachel Lewis delivered a speech at a Taiwan Ocean Affairs Council event, emphasizing the importance of intelligence sharing. This was a rare moment: a serving U.S. military officer speaking publicly in Taiwan since diplomatic ties were severed in 1979.
"Only through cooperation can we take timely and effective action," Lewis told CommonWealth Magazine, stressing that Taiwan must work closely with international partners.
Indo-Pacific Strategies and the Defense of Freedom of Navigation
Previously undisclosed diplomatic collaborations have gradually come to light. The driving force behind this shift is the rise of the Indo-Pacific strategy in global security planning.
In 2017, during his first term, former U.S. President Donald Trump redefined the geopolitical framework by introducing the term “Indo-Pacific” to replace “Asia-Pacific,” expanding the strategic focus from the Asia-Pacific to the Indian Ocean.
“No matter how big or small a nation is, all countries must respect each other, enjoy the freedom of navigation, and resolve disputes peacefully,” then-U.S. Secretary of Defense James Mattis declared at the 2018 Shangri-La Dialogue in Singapore. At the heart of this strategy was the protection of maritime freedom.
Since then, U.S. and allied naval forces have become a common sight across the Indo-Pacific—from the Indian Ocean and the South China Sea to the western Pacific, including the Taiwan Strait.
Meanwhile, China’s navy has continued its outward expansion, with the South China Sea and Taiwan Strait becoming key areas of focus.
As U.S. and Chinese naval forces increasingly encounter each other in these waters, the Taiwan Strait has emerged as the latest geopolitical flashpoint.
According to publicly available records, the U.S. Seventh Fleet has maintained regular patrols through the Taiwan Strait. Additionally, countries such as Australia and the United Kingdom (both U.S. AUKUS allies), as well as Canada, France, and others—at least nine nations in total—have conducted high-profile transits through the strait over the past three years.
In a particularly noteworthy event last September, two German navy frigates passed through the Taiwan Strait en route to Hawaii for the Rim of the Pacific (RIMPAC) exercises—the first such transit by Germany in 22 years. “International waters are international waters,” German Defense Minister Boris Pistorius later affirmed.
However, National Defense University professor Ma Chen-Kun has cautioned that while these naval transits challenge Beijing’s territorial claims, China often shadows foreign warships with its own vessels, reinforcing its own navigational presence.
Trump’s Return Unlikely to Change the Taiwan Strait Reality
Diplomatic sources in Taipei emphasize that regardless of whether Donald Trump returns to office and disrupts international norms, the strategic importance of the Taiwan Strait remains unchanged.
At the core of this issue is the sheer scale of global trade dependent on this narrow waterway.
A report from the Center for Strategic and International Studies (CSIS) last year highlighted Taiwan’s critical position along the First Island Chain. Over 20% of the world’s maritime trade passes through the Taiwan Strait. In 2022 alone, goods worth at least $2.45 trillion—including energy, electronics, and minerals—traversed these waters.
Jim Nickel, Canadian Representative to Taiwan. (Photo: Chien-Tong Wang)
In other words, any disruption in the strait would severely impact global supply chains.
“Canada’s Indo-Pacific strategy is not driven by ideology, but by reality,” Canadian Representative to Taiwan Jim Nickel stated in an exclusive interview.
Since Canada introduced its Indo-Pacific strategy in 2022, its naval presence in the Taiwan Strait has been second only to that of the United States.
“In the coming years, we will continue our regular and consistent transits,” Nickel confirmed. “Regardless of geopolitical changes, the Indo-Pacific remains a priority.”
This may be an unintended consequence of China’s aggressive “gray zone” tactics: The Taiwan Strait is no longer just Taiwan’s concern—it has become a shared interest for the world.
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