A United States special mission vessel—designed to monitor missile launches—was spotted underway off China’s coast in the Yellow Sea last month, according to ship-tracking data.

Newsweek reached out to the U.S. Seventh Fleet, which is responsible for America’s naval operations in the western Pacific, and China‘s Defense Ministry for comment via email.

Why It Matters

Under the Special Mission program, the U.S. Navy‘s Military Sealift Command operates approximately 20 ships, including the USNS Howard O. Lorenzen, the country’s only missile range instrumentation ship, which provides support for military and other government missions.

The presence of the Howard O. Lorenzen—capable of collecting data on missile launches—near the Chinese coastline comes as the Pentagon warns of a growing missile threat posed by China to U.S. bases, allies, and partners in the Indo-Pacific region.

Another U.S. “Special Mission” ship, the ocean surveillance ship USNS Victorious, was tracked operating in the contested South China Sea from late May to early June. The ship is designed to collect undersea acoustic data in support of anti-submarine warfare development.

What To Know

Using open-source ship-tracking data, a Newsweek map shows that the Howard O. Lorenzen was underway in Sasebo Bay, located in western Japan, on June 6. It later transited across the East China Sea and reached the Yellow Sea to the northwest, near China’s eastern coast.

The American missile-tracking ship was last tracked in the Yellow Sea on June 26, about 100 miles off the Chinese coastline—well beyond the country’s 13.8-mile-wide territorial waters—and near Yuchi Naval Base, home to China’s first aircraft carrier, CNS Liaoning.

The mission of the Howard O. Lorenzen near China remains unclear. Equipped with a radar system known as Cobra King, the 12,642-ton ship serves as the sea-based component of the Pentagon’s Cobra program, monitoring missile and space launches, according to the U.S. Air Force.

The Chinese military has yet to announce any missile launches, and it is unclear whether the Howard O. Lorenzen was shadowed by the Chinese navy while operating in the Yellow Sea.

In addition to the deployment of a missile-tracking ship, a U.S. Air Force RC-135S Cobra Ball aircraft—capable of collecting optical and electronic data on ballistic targets—was spotted flying over the Yellow Sea on June 24, according to open-source flight-tracking data.

The sensor-equipped aircraft was launched from Kadena Air Base, a U.S. airpower outpost on Japan’s Okinawa Island. It arrived for forward deployment in early June, replacing another Cobra Ball aircraft that was returning to Offutt Air Force Base in Nebraska.

What People Are Saying

The U.S. Navy’s Military Sealift Command said: “Missile range instrumentation ships serve as platforms for monitoring missile launches and collecting data that can be used to improve missile efficiency and accuracy. These ships monitor foreign missile and weapons tests that may pose potential threats to air or surface navigation.”

The U.S. Air Force said: “The RC-135S, equipped with a sophisticated array of optical and electronic sensors, recording media, and communications equipment, is a national asset uniquely suited to provide America’s leaders and defense community with vital information that cannot be obtained by any other source.”

What Happens Next

It remains to be seen how long the Howard O. Lorenzen will remain deployed in the Yellow Sea, and whether other “Special Mission” ships will operate in waters surrounding China.