Since 1996, the Chinese military has steadily expanded its umbrella of land-based missiles, strike aircraft, and submarines designed to overwhelm both US air bases and carrier strike groups. That buildup aims to discourage the US military from potentially intervening in China's territorial disputes with neighboring Asian countries. Now, the US response appears to be taking shape, first in the form of a new use for an old weapons system.

In late 2016, the Pentagon announced that it would convert the Army Tactical Missile System (ATACMS), a weapon typically fired from a truck-mounted rocket launcher, into a guided ballistic missile capable of hitting moving warships. That represents a planned upgrade of an existing Army missile that can strike targets at distances of about 186 miles. It could also form the linchpin of a US "forward defense" strategy meant to keep China from becoming too aggressive with its growing naval power.

“For a long time, the US has taken air and sea supremacy for granted,” says Cmdr. Keith Patton, deputy chair of the Strategic and Operational Research Department at the US Naval War College in Newport, Rhode Island. “Now the military is looking back again to see what can be done and what can be defended; people are rediscovering their past.”

Sea Change

Conversion of the Army missile into a ship-killing weapon is a “logical step” given US security concerns in the near future, says Patton. The weapon already has a proven combat record from the 1991 Gulf War and the post-9/11 wars in Iraq and Afghanistan. And if not for limitations imposed by the Intermediate Range Nuclear Forces Treaty, it could have even greater long-distance strike capability.

The shift to the sea represents a sharp change from the US Army's focus for most of the past 70 years. While coastal artillery guns still played a role in WWII, the dominance of long-range bombers and aircraft carriers eventually made large, fixed guns obsolete as shore defenses.

“After World War II, the US was seen as unchallenged at sea, with the possible exception of Soviet submarines,” Patton explains. “Coastal defense artillery, or even missiles, could not help with that threat, and would have been a distraction to Army's primary mission of winning a major land war in Europe.”

These days, the US no longer holds such a clear oceanic advantage. China has the world's largest conventional ballistic missile force, and two different types of anti-ship ballistic missiles designed to kill ships such as US Navy carriers. By 2020, the Chinese military will also match or exceed the US military in number of surface-to-air missiles (SAMs) and anti-ship cruise missiles, said Andrew Erickson, professor of strategy in the US Naval War College's China Maritime Studies Institute, during a hearing for the US-China Economic and Security Review Commission on Feb. 23. He added that China would "unambiguously" have the world's second-largest blue water navy by 2020.

China's growing naval power has inadvertently highlighted the gaps in US anti-ship capabilities. The US military's primary anti-ship weapon has been the sea-skimming Harpoon missile that flies slower than the speed of sound. By comparison, ATACMS with an upgraded guidance system could become a ballistic anti-ship weapon that dives toward targets at speeds of up to Mach 3.

Scoot and Shoot

The US Army already plans to train for its "multi-domain battle" role in possibly firing land-based missiles at enemy warships. Such anti-ship weapons may also end up being sold to US allies in the Pacific. It's one thing for an adversary to target a huge US aircraft carrier or static air base, but it's another matter entirely to try tracking dozens of mobile missile launchers mounted on trucks. "With an aircraft carrier or an airfield, you could hit the runway and disable it for a while," Patton says. "But the US military has learned how hard it is to track small, missile-launched vehicles."

The shoot-and-scoot mobility of rocket trucks is just one advantage of the land-based missile systems, says David Johnson, a senior fellow at the Center for Strategic and Budgetary Assessments in Washington, D.C. Unlike anti-ship weapons carried by aircraft or naval vessels, land-based weapons can have "deep magazines," with no serious physical limitation on the number of missiles available. And the ATACMS conversion may just be the start, as the US military develops a next generation of land-based missiles that could target ships in any military theater of operation.

"ATACMS is attractive because it's already been developed—you may have to change the guidance technology, but it's an approved system," Johnson says. "Whether it's an interim solution or just an idea to start thinking of how to solve the problem, long-ranged fire is an advantage that these systems will bring to those theaters that will complement joint military operations."

That aligns with recent US military strategic thinking on the Pacific. A 2013 RAND report sponsored by the US Army suggested that "the strategic placement of anti-ship missile systems" could help deter open conflict by "significantly raising the cost for China," or actively "interdict warships" or "be used to form a full blockade of critical waterways in times of war."

Land-based missiles may also offer a solution to a current dilemma faced by the US military in supporting Asian countries that often face off with China over competing territorial claims. The U.S. has traditionally relied on forward air bases and carrier strike groups—such as the USS Carl Vinson group that embarked on a patrol of the South China Sea in February—to provide highly visible reassurance to allies in the Pacific-Asia region. But such high-visibility military assets are also the most vulnerable to China's many missile-armed forces if it came to open conflict.

The US military could sidestep this dilemma if it chose to "emulate China by fielding mobile, land-based missile forces of its own," said Evan Montgomery, a senior fellow at CSBA, in a recent report titled "Reinforcing the Front Line: US Defense Strategy and the Rise of China." Land-based anti-ship missiles positioned on the territory of U.S. allies could provide the same reassurance while also being much less vulnerable militarily—and perhaps reduce the overall risk of open war by acting as a powerful deterrent.

There is always the possibility that China would take a dim view of US military moves to reinforce its allies with land-based missiles. But any potentially stabilizing strategy beyond the status quo would be welcome, as tensions in the South China Sea continue to bubble and brew.