What is the 'nine-dash line' and what does it have to do with the Barbie movie?

The new Barbie film starring Margot Robbie and Ryan Gosling is set for imminent release. But according to Vietnam’s state-run Tuoi Tre newspaper the film’s release has been barred. The head of the Department of Cinema, a government body in charge of licensing and censoring foreign films, said

We do not grant license for the American movie ‘Barbie’ to release in Vietnam because it contains the offending image of the nine-dash line

Vietnam’s response to the Barbie movie’s depiction of the South China Sea shows how sensitive these matters are in South East Asia, and especially in Vietnam.

What is the nine-dash line?

The South China Sea has a long history of being contested.

China and Vietnam engaged in military clashes over the Paracel and Spratly Islands in the South China Sea in 1974 and 1988.

Those disputes were over land, but more recently the focus has turned to claims over the continental shelf (the area of seabed that extends beyond the coast to at least 200 nautical miles), and the economic zones (the area at least 200 nautical miles from the coast).

Since the late 1940s, China has promoted the so-called nine-dash line in the South China Sea. The line, also known as the “U-shaped line” or “cow’s tongue” comprises nine dashes.

As depicted in various official and unofficial Chinese maps, the line extends off the coast of China’s Hainan Island, and runs close to the coast of Vietnam, deep into the South China Sea, enclosing the Spratly Islands.

North of Borneo, near the coasts of Malaysia and Brunei, the line turns and runs to the west of the Philippines and ends just to the south of Taiwan.

The line has long been the subject of speculation as to what exactly it purports to encompass. Is it a Chinese territorial claim? Is it a Chinese claim to a maritime space? Does it extend to sovereignty over the whole area or just to resources?

China has never been very explicit as to precisely what the claim includes but it has been persistent in seeking to advance the claim.

This has especially been the case since Malaysia, the Philippines, and Vietnam have begun to advance their own claims to parts of the South China Sea, which overlap the nine-dash line.

Who disputes the line?

A 2009 joint Malaysia/Vietnam submission to the United Nations Commission on the Limits of the Continental Shelf highlighted competing claims over the continental shelf in the South China Sea, which is what sparked the current controversy.

China made a formal diplomatic response to the UN claiming:

China has indisputable sovereignty over the islands in the South China Sea and the adjacent waters, and enjoys indisputable sovereign rights and jurisdiction over the relevant waters as well as the seabed and subsoil thereof (see attached map).

China attached a copy of the nine-dash line map to its formal diplomatic protest to the Malaysia/Vietnam submission and added

The above position is consistently held by the Chinese Government, and is widely known by the international community.

It turned out, however, that this was not a widely known or shared view by the international community. Since then the commission has become something of a de facto legal battleground for various views regarding the status of the nine-dash line.

In addition to China continuously advancing its position regarding the legitimacy of the nine-dash line, countries including Australia, France, Indonesia, Malaysia, New Zealand, the Philippines, United Kingdom, and Vietnam have rebutted China’s assertions.

But the commission is not a court and is comprised of scientists who assess continental shelf claims.

It was up to the Philippines, as the other nation with possible claims on the region, to separately challenge the legality of China’s nine-dash line claim under the law of the sea. In 2016, a United Nations Law of the Sea Convention Tribunal ruled unanimously that China’s claim had no basis in international law.

That ruling was clear-cut and conclusive, and immediately rejected by China. While the Philippines conclusively won the legal argument that the nine-dash line had no basis in modern international law or the law of the sea, China refused to respect the outcome of that case and continues to assert its South China Sea entitlements.

China does this in multiple ways. It has built artificial islands in the South China Sea, harassed foreign naval and military aircraft passing through the region, intimidated Vietnamese and other foreign fishermen, asserted rights to explore and exploit maritime oil and gas reserves, and continued to publish maps depicting the nine-dash line claim.

This is why any legitimacy given to the nine-dash line, even in Hollywood movies, is so sensitive.

Why are maps so controversial?

Maps are reflective of a critical national attribute: territory.

They define the outer limits of territorial claims. Children are familiarised with their home country by maps. Maps have historically been depicted on postage stamps, buildings, and more recently government websites.

Maps now depict a country digitally and this has become contested, as highlighted by the Russian invasion of Ukraine.

University students challenge their professors when maps are shown that depict disputed lands.

Maps have meaning and touch national sensitivities.

Vietnam’s response to Hollywood’s depiction of China’s nine-dash line is understandable. It demonstrates a fierce resistance to any legitimacy that China’s ongoing South China Sea nine-dash line claims may generate, even in Barbie’s fictional world.