From airspace to sea lanes: A new front in US-China rivalry

The obstruction of Taiwan President Lai Ching-te’s visit to Eswatini and the ongoing dispute between the US and Iran over the blockade of the Strait of Hormuz have been among the world’s major geopolitical flashpoints in recent days. 

Both cases reveal how major powers are leveraging control and influence over critical nodes — such as airspace and sea lanes — turning what should be international public goods serving security and free movement, into instruments for advancing political objectives.

On the eve of Lai’s planned visit to Eswatini on 22 April, the Presidential Office announced that Seychelles, Mauritius and Madagascar — through whose airspace the presidential aircraft was to pass — had abruptly revoked overflight permits under pressure from Beijing. Following a security assessment, the trip was postponed, with a special envoy sent in his stead.

After US lawmakers spoke out in condemning Beijing’s pressure, a Taiwan State Department spokesperson formally expressed concern on 22 April, characterising the episode as an abuse of the international civil aviation system.

Speaking to Reuters, the spokesperson said: “These countries are acting at the behest of China by interfering in the safety and dignity of routine travel by Taiwan officials.”

The spokesperson also criticised African countries’ management of certain international airspace beyond their sovereign limits, arguing that it should serve aviation safety alone rather than be used as a political tool.

British Office Taipei representative Ruth Bradley-Jones and an EU spokesperson also expressed concerns, stressing that decisions over airspace management should not be used to achieve political ends.

In response to the US accusations, Chinese foreign ministry spokesperson Guo Jiakun asserted at a regular press briefing on 23 April, “It is fully just for China to defend national sovereignty and territorial integrity, and for relevant countries to safeguard the one China principle. The US’s irresponsible accusations are nothing but a mischaracterisation of the facts and truth. China firmly opposes it and will never accept it.”

Although Beijing denies exerting pressure and insists the countries involved acted in accordance with the “one China” principle, the episode nevertheless highlights how airspace and overflight permits are no longer purely technical or administrative matters, but can also be shaped by diplomatic pressure and political signalling.

Sung Wen-Ti, a non-resident fellow with the Atlantic Council’s Global China Hub, told Lianhe Zaobao that this amounts to the “weaponisation of the sky” — in other words, the politicisation of what has traditionally been a largely apolitical domain of governance.

He thinks that while Beijing was previously unable to prevent foreign dignitaries from visiting Taiwan, it is now going a step further by seeking to restrict Taiwan’s leaders from entering other countries. This can be seen as a form of “aerial containment” aimed at reducing Taiwan’s international saliency.

However, in the Strait of Hormuz, the US is also leveraging its influence over key maritime chokepoints to demonstrate a more powerful and stronger level of strategic manoeuvring.

The Strait of Hormuz is one of the world’s most important energy transit chokepoints, carrying around a quarter of global seaborne oil and one-fifth of liquefied natural gas (LNG) shipments. Since the escalation of US-Israel tensions with Iran around 28 February, passage through the strait has been disrupted. Although the US and Iran agreed to a ceasefire in early April, Iran has continued to require vessels to sail close to its territorial waters, and at the time, throughput fell to less than 10% of normal levels.

Subsequently, after peace talks broke down, US President Donald Trump announced a maritime blockade on vessels entering and leaving Iranian ports, which took effect on 13 April. By 22 April, Iran’s Islamic Revolutionary Guard Corps had also seized two cargo ships in the strait, stating that until the US blockade is lifted, reopening the Strait of Hormuz “is not possible”.

Overall, since the escalation of the conflict, the transit order in the Strait of Hormuz has shifted from a standard “open shipping lane” to a high-risk zone shaped by reciprocal blockades, interceptions and vessel seizures by both the US and Iran.

Qin Tian, deputy director of the Institute of Middle East Studies at the China Institutes of Contemporary International Relations, told CCTV News that such a maritime blockade can be seen as a “middle ground option” in US policy towards Iran. It maintains pressure while avoiding further escalation of the conflict, serving as a middle ground measure.

Qin noted that the blockade is also seen as an important shift in US pressure tactics from military strikes towards economic coercion. By disrupting Iran’s heavy reliance on oil and gas exports through the Strait of Hormuz, it aims to test the resilience of the Iranian economy and increase bargaining leverage in negotiations.

This also reflects the fact that key maritime chokepoints have now become multifunctional instruments combining deterrence, sanctions and negotiation leverage.

Seen together, Lai’s disrupted visit and the blockade tensions in the Strait of Hormuz point to a broader pattern: whether in international airspace, flight information regions, or maritime chokepoints and port routes, the key transit points that sustain the everyday functioning of globalisation are increasingly being turned into tools by major powers to exert pressure, constrain room for manoeuvre and shape the terms of negotiation.

Wang Hung-Jen, a political science professor at Taiwan’s National Cheng Kung University, told Lianhe Zaobao that when things that are originally public, institutional or infrastructural in nature are used as tools of pressure, bargaining or punishment, they become “politicised”. If they further raise or alter security risks, they take on a stronger “weaponised” character. Thus, the two incidents are merely manifestations of the same phenomenon at different levels.

This trend has a particularly profound impact on small- and medium-sized countries, as most of them lack the ability to reshape international rules, yet are highly dependent on the stability of shipping routes, maritime passages, energy transport and cross-border institutional arrangements.

Wang added that China-US competition is no longer confined to the military sphere, but has extended into technology, discourse and leadership over the international order. In the absence of a willingness to resort to direct military conflict, both powers are increasingly likely to rely on control over key nodes such as sea lanes, ports, communications networks and even undersea cables to constrain each other’s room for manoeuvre and access to resources. “These key transit points are becoming important tools for weakening an opponent’s capabilities without going to war.”

He believes that the current situation presents a complex, multi-layered challenge, saying, “Amid great power rivalry, this kind of pressure may ultimately force small- and medium-sized countries to choose sides.”

This article was first published in Lianhe Zaobao as “航道空域公共资源成大国竞逐工具 中小国恐被迫站队”.

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