In March, Vietnam's government commemorated a deadly 1988 clash with China in the South China Sea.
The ceremony was a rare one, as Hanoi has long avoided public discussion the battle with its larger neighbor.
This year's ceremony, taking place amid Russia's attack on Ukraine, was seen as a quiet message to Beijing.
In a ceremony at a memorial to the battle in Khanh Hoa province, Chinh laid a wreath, burned incense, and wrote a tribute to those killed in the fighting. The ceremony was accompanied by a front-page editorial in Nhân Dân, the official newspaper of the Communist Party of Vietnam.
The actions may seem unremarkable, but they were actually unprecedented.
Vietnam has long avoided officially discussing or commemorating the battle, which was a stinging defeat and remains a source of anti-Chinese sentiment. In previous years, citizen-organized memorial events and demonstrations marking the battle have even been suppressed by Vietnamese authorities.
The official reticence stems largely from a desire to keep that anti-Chinese sentiment from growing and to avoid antagonizing Beijing, which is Vietnam's largest trading partner.
But the high-profile commemoration this year, along with Vietnam's recent actions in the South China Sea and its own military investment plans, may be a message from Hanoi to its larger, better-armed neighbor.
A complicated history and long-standing dispute
Johnson South Reef is part of the Spratly Islands, a group of over 100 islands, rocks, reefs, and other features in the South China Sea about 500 miles west of Vietnam's southern coast.
With a total area of about 7.2 square kilometers, Johnson South Reef only has a few stretches that are naturally above water for a few hours a day during low tide. Johnson South Reef and several other features make up an area known as Union Banks, which forms the southwestern part of the Spratly Islands.
The Spratly Islands, like other islands in the South China Sea, have long been the subject of intense territorial disputes.
Beijing has made sweeping claims over the region that have been challenged by its neighbors, many of which have their own claims. An international tribunal has also ruled that Beijing's claims to rights within what it calls "the nine-dash line" were without legal basis.
China and Vietnam's history make their South China Sea disputes unique. As a fellow single-party communist state, China was Vietnam's biggest supporter as it fought France, South Vietnam, and the US - but historical divisions kept Beijing and Hanoi from forming an ironclad alliance.
In 1974, China attacked and seized the all of the Paracel Islands from South Vietnam in a days-long naval battle that killed or wounded about 100 South Vietnamese soldiers, sank 1 corvette, and damaged three frigates.
Despite being at war with the South, Hanoi protested Beijing's actions because it had its own claims on the Paracels but ultimately did nothing because it faced more pressing matters on the mainland.
Sino-Vietnamese relations didn't get much better after Hanoi defeated South Vietnam in 1975. In 1979, the two countries fought an intense border war that lasted less than a month but caused large casualties and intermittent clashes in the area until 1991.
Johnson South Reef
Following the 1979 war, tensions between China and Vietnam in the South China Sea increased.
By the late 1980s, China began to assert its claims to the Spratly Islands more aggressively, and in 1988 it began deploying soldiers and maritime militia on some of the islands, such as Fiery Cross Reef.
Vietnam vigorously protested and began deployments of its own, a number of which were to the islands and reefs of Union Banks.
Between March 11 and March 13, 1988, two armed Vietnam People's Navy transport ships and a landing ship were sent with some 100 soldiers and building materials to make outposts on Johnson South Reef, Collins Reef, and Lansdowne Reef.
The Chinese had deployed to nearby Hughes Reef, which was under their control. By March 14, three Chinese frigates were in the area, monitoring the Vietnamese.
It remains unclear how battle erupted on the morning of March 14.
The Vietnamese claim that their landing parties, who had placed multiple flags on the then-submerged Johnson South Reef, were confronted by Chinese soldiers who demanded that they leave. After an attempt to dislodge them failed, the Chinese frigates opened fire with 37mm anti-aircraft and 100mm naval guns.
The Chinese claim that the Vietnamese on the reef and on one of the transport ships fired on them first.
Regardless of how it started, the battle was a total defeat for the Vietnamese. Unable to hide or move on the submerged reef, 62 Vietnamese sailors and naval infantry were mowed down in a matter of minutes. The Chinese frigates then turned to the VPN ships and sunk the transports, killing two more Vietnamese sailors.
The Vietnamese landing ship was damaged and its crew beached it on Collins Reef, where it was destroyed. By the end of the day, 64 Vietnamese were killed, nine were captured, three ships were sunk or destroyed, and Johnson South Reef was under Chinese control.
Preparing for the future
Vietnam's official commemoration of the battle at Johnson South Reef this year was seen as an assertion of sovereignty and as a reminder of how Hanoi had defied its larger neighbor in the past - a message made necessary by Russia's attack on Ukraine.
In the years since the battle, China has worked to turn the reefs and islands that it controls in the South China Sea into small fortresses. Through land reclamation, China has expanded existing features and built artificial islands to which it has deployed weapons and troops.
Today, Johnson South Reef has a 27-acre artificial island with a port, helipad, a radar station, and close-in weapon systems for air and missile defense.
Vietnam still claims all of the Spratlys, and it has tried to bolster the defenses on the islands still under its control.
Vietnam has also improved its relations with its neighbors in recent years, likely with the goal of countering China. Hanoi has joined naval exercises with India and Japan, hosted Australian navy ships, and improved ties with its old enemy, the US.
Though China and Vietnam have close economic ties, their tensions have never truly faded. As Beijing continues to bolster its military and grow its reach, Vietnam is looking to make sure it can defend its interests and avoid a repeat of the events in 1988.