SINGAPORE (Reuters) – Chinese strikes on airfields will stymie U.S. military aircraft in the Indo-Pacific region if there is a conflict, a new study says, recommending that the United States invest in cheap, uncrewed aircraft and runway repair capabilities.

The central problem, the researchers say, is that bases inside the first island chain – a collection of archipelagos running roughly from Indonesia in an arc northeast to Japan, encompassing the South China Sea and East China Sea – are in range of thousands of Chinese missiles.

If those weapons are dedicated to destroying or disabling runways, they could close airfields in Japan for a minimum of 11.7 days. Those farther away, in Guam and the Pacific Islands, could be closed for a minimum of 1.7 days.

“In practice, however, China could disrupt U.S. combat operations for much longer by denying the United States the use of runways to conduct aerial refuelling operations,” the report states.

The report, “Cratering Effects: Chinese Missile Threats to US Air Bases in the Indo-Pacific,” was published on Thursday by the Stimson Center, a defence and security think tank.

It recommends investing in a large number of inexpensive, uncrewed aircraft and electronic warfare to complicate Chinese strike planning; developing more crewed aircraft that can operate with short runways; developing more runway-repair and base resilience capabilities; and nurturing alliances so that friendly countries are more willing to open airfields for U.S. use.

U.S. Indo-Pacific Command, which oversees American forces in the region, did not respond to a request for comment.

China’s ministry of defence did not respond to a request for comment.

U.S. military planners have in recent years built around the concept of distributed operations – spreading forces throughout the region. As part of the Pacific Deterrence Initiative, hundreds of millions of dollars have been spent upgrading airfields in places such as Australia and the island of Tinian.

In recent years the Air Force also developed a program called Rapid Airfield Damage Recovery (RADR), the report noted, meant to reopen runways quickly after an attack and keep them active for “thousands” of sorties.

The U.S. is also counting on missile defences – it is planning a multibillion-dollar “layered” network of interceptors to protect Guam – to keep airfields and other bases operating.

A former U.S. Air Force logistics officer with direct knowledge of Indo-Pacific conflict simulations said the report offered a good assessment of the problem.

The officer said RADR and missile defences would be more effective than the report estimated, and noted that Chinese strike planners would most likely use a mix of munitions rather than 100% anti-runway submunitions, as the report assumed.

“While I don’t think I much agree with the exact numbers… I do agree that the analysis is broadly directionally correct,” said the officer, speaking on condition of anonymity because of the sensitivity of the matter.

The report calculated the effect of Chinese strikes by creating a statistical modelling script in Python that considered variables such as runway size, Chinese weapon accuracy and U.S. defences.

“In the last year, I started to hear more and more policymakers and analysts suggesting that it would be feasible for the United States to sink enough Chinese vessels and defend Taiwan so long as the United States had access to bases in Japan and Guam,” said Kelly Grieco, one of the report’s authors. “At least in open source, no one had tested these propositions.”