Vietnam and China boast strong economic and political ties. In 2008, the two authoritarian regimes established a "comprehensive strategic partnership" that has not only fostered cooperation and stability but also strengthened trade, with bilateral commerce exceeding $171 billion (€159 billion) in 2023. 

But despite this close cooperation, the two Asian nations have struggled to defuse tensions over disputed territory in the South China Sea, a strategically significant and resource-rich waterway. Beijing and Hanoi both assert sovereignty over the Spratly and Paracel Islands, which sit hundreds of kilometers from both countries.

Beijing is currently undergoing a significant military expansion and has adopted a more aggressive stance in asserting its territorial claims. As a result, direct confrontations with neighboring countries have become more frequent. While the Philippines is the primary focus, the crisis also involves Vietnam, Taiwan, Malaysia and Brunei.

Frail friendship between Vietnam and China? 

The dispute over the islands grabbed headlines in May when Vietnam protested a Chinese navy hospital ship being deployed within the Paracel Islands to treat some Chinese soldiers.

It prompted Vietnam's newly elected president, To Lam, to insist that the neighbors resolve disagreements at sea and "respect each other's legitimate rights and interests."

Lam's comments sparked discussions about whether Hanoi's relations with Beijing were fraying.

What is the dispute over?

China gained control of the Paracel Islands in 1974 from then-South Vietnam after a battle for the archipelago. But Vietnam maintains its sovereignty rights based on the 1982 United Nations Convention on the Law of the Sea (UNCLOS), which plays a crucial role in resolving disputes in the South China Sea.

Vietnam's opposition to China controlling the islands is nothing new, according to Postdoctoral Fellow Bich Tran at the Lee Kuan Yew School of Public Policy in Singapore.

"Vietnam's protest against China's hospital ship near the Paracels shows its position on the Paracels is firm. Vietnam has taken every opportunity to reiterate its sovereignty over the islands," she said.

Tran pointed out that President Lam's comments are not a change of direction on the matter.

How will they resolve the conflict?

In 2011, China and Vietnam entered into an agreement to manage their maritime disputes. The primary objective was to prevent tensions from escalating and maintain stability in the region.

The agreement reaffirmed Beijing and Hanoi's commitment to a two-decade-old conduct agreement and emphasized the significance of resolving conflicts in cooperative and mutually beneficial ways. 

"Vietnam's approach toward China regarding the SCS [South China Sea] has been consistent with the agreement on basic principles guiding the settlement of sea-related issues that the two countries signed in 2011," Bich Tran told DW.

The latest escalation between Vietnam and China comes at a time when the Philippines has increased its resistance to Beijing's territorial claims in the South China Sea.

The two nations have traded barbs for months over dangerous maneuvers at the Second Thomas Shoal, called Ayungin Shoal by the Philippines, which is part of the disputed Spratly Islands.

Tussles on the high seas

Second Thomas Shoal is in an area militarily occupied by the Philippines but claimed by several countries, including China.

China has long expanded existing islands and even built new ones for military purposes in the South China Sea.

But in recent years, Vietnam has been increasing its dredging and landfill work, too.

"What is new is that Vietnam started to adopt cutter suction dredgers — the method that China has used — which increases the speed," Tran said.

Despite Hanoi's island expansion, Beijing is less concerned than it is with Manila, said Collin Koh, senior fellow at the Institute for Defense and Strategic Studies at the S. Rajaratnam School of International Studies in Singapore.

"Vietnam has been resupplying its garrisons in the Spratlys, conducted its own island construction and infrastructure expansion programs, but China has not actively interfered with them at all —  unlike in the case of the Philippines, which has seen this repeated series of run-ins with China since last February," Koh wrote in an email.

Will Hanoi ask Washington for help?

Despite the mutual understanding between the two strict communist regimes in Asia, Koh believes that Vietnam will stand firm against China on the territory disputes.

"Vietnam isn't likely to yield from its position on the South China issue, and all it seeks is to properly manage the problem with China."

At the same time, "Vietnam also doesn't appear keen to rock the boat with China because it's still grappling with economic and domestic political issues," according to Koh.

"Conflict management rather than resolution would still be the way forward," he said.

The Singapore-based expert believes Hanoi will take a strategic approach, having tightened relations with China's biggest rival, the United States.

Washington and Hanoi only resumed diplomatic relations in 1995, two decades after the end of the Vietnam War. Ties entered a new phase when the former adversaries signed a "comprehensive strategic partnership" in September.

"Vietnam appears keen to demonstrate its ability to hedge — where it concerns the [South China Sea] issue, Hanoi could at least remind Beijing that it does have some powerful friends it can tap if push comes to shove," he added.

Edited by: Keith Walker

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