China is deploying airships in the South China Sea.

An Israeli satellite imagery company has posted a photo of an aerostat – a tethered balloon – floating over a Chinese island-base in the disputed region.

“For the first time, # China's aerostat, probably for # military # intelligence-gathering purposes, seen by # ISI at # Mischief Reef,” tweeted Imagesat Intl. The use of # aerostat allows China a continuous situational awareness in this resource-rich region.”

Mischief Reef is an atoll enclosing a lagoon to the east of the Spratly Islands. China has constructed an artificial island on the reef, that includes a harbor and airfield. This is one of several Chinese artificial islands in the region, which are armed with anti-ship and anti-anticraft missiles, radar, runways and barracks. They are Beijing’s way of attempting to permanently assert its sovereignty over the South China Sea, whose waters – rich in oil and other natural resources – are claimed by several nations, including Vietnam, the Philippines and Taiwan.

China has been building an early-warning system of aerostats since 2017, according to the South China Morning Post. “Huge balloons were fitted with phased-array radars to help detect low-flying incoming planes,”

“Aerostats are being deployed in some of China’s strategic hotspots such as the country’s border with North Korea and the Taiwan Strait,” said the Post. “According to Kanwa Asian Defense, the high-powered aerostats can monitor both airborne targets and mobile ground objects within a radius of 300km (186 miles).”

“The reef covers 5.5 square kilometers (2.1 square miles) and boasts an airfield capable of handling an Airbus A320,” the Post noted. “It also has a lighthouse and other military and civilian facilities. In 2016, an international tribunal ruled that because the outpost was a reef that was submerged at high tide, it did not qualify for 12-nautical mile territorial waters. It has since become a focus of the U.S. Navy’s challenges to China’s ‘excessive claims’ in the waters, and has been the target in six of 21 ‘freedom of navigation’ operations in the past few years.”

Meanwhile, Indian media claimed in June 2019 that China has deployed Russian-made aerostats in Tibet, with the goal of spying on Indian territory. “Modern-day China began to show interest in aerostats in the 1990s, but it was only in 2010-11 that it received three large-sized tethered aerostat systems from the Russian company Augur-RosAero Systems,” according to Indian newspaper The Print. “These ‘Puma’ aerostats are primarily designed to carry an early warning radar station and can be raised to a height of 5,000 meters [5,468 feet]. Satellite images have shown the Pumas deployed at three locations, and even flying at one site at a height of 5 kilometers [3.1 miles] above ground level.”

Military aerostats are also used by the U.S., Russia, Israel and other nations. Equipped with radar and other sensors, and tethered to the ground by a cable, aerostats are a cheap – albeit immobile -- alternative to manned aircraft and drones. They also illustrate the value of China’s artificial island-bases in the South China Sea. While these bases are fixed installations on small chunks of bare land that vulnerable to attack, they also provide a permanent launching pad for platforms such as aerostats in a way that a floating U.S. Navy carrier battlegroup cannot.

Michael Peck is a contributing writer for the National Interest. He can be found on Twitter and Facebook.