The United States has been ramping up its Indo-Pacific region air bases to ensure they are protected against attack, a spokesperson for the U.S. Pacific Air Forces told VOA this week, amid concerns over vulnerabilities they face in countries such as Japan, the Philippines and South Korea against potential Chinese strikes.

“While we are continually improving our theater posture, warfighting advantage and integration with allied and partners, Pacific Air Forces stands ready every day to respond to anything that poses a threat to a free and open Indo-Pacific,” the spokesperson said.

“We continue to invest in infrastructure and technology to enhance the resilience and survivability of our bases and facilities across the theater, including hardening airfields and buildings while investing in advanced security systems to protect our personnel and assets,” the spokesperson told VOA on Tuesday.

The Air Force was authorized with “$916.6 million to improve logistics, maintenance capabilities and prepositioning of equipment, munitions, fuel and material in the Indo-Pacific” through the fiscal 2024 Pacific Deterrence Initiative, the spokesperson added. The Pacific Deterrence Initiative is a set of defense priorities set up in 2021 by Congress to support U.S. goals in the Indo-Pacific, primarily to counter China.

The comments were made in response to a report last week by the Hudson Institute claiming that U.S. aircraft at allied Indo-Pacific country bases could suffer major losses from Chinese attacks unless those bases are fortified.

If left unfortified, the U.S. air power in the region would be significantly reduced compared to China’s, according to the report, Concrete Sky: Air Based Hardening in the Western Pacific.

One of the reasons, according to the report, is that the U.S. is lagging behind China in the number of shelters that could hide and protect the aircraft from attacks.

China more than doubled the number of aircraft shelters since the early 2010s, having more than 3,000, according to the report. Across 134 Chinese air bases located within 1,000 nautical miles of the Taiwan Strait, China has more than 650 hardened aircraft shelters and nearly 2,000 nonhardened individual aircraft shelters.

A hardened shelter is a reinforced structure made of steel, concrete, and other materials to protect military aircraft from enemy strikes.

In comparison, the U.S. has added two hardened shelters and 41 nonhardened ones within 1,000 nautical miles of the Taiwan Strait and outside South Korea since the 2010s, the report said.

This means if a war breaks out over Taiwan, U.S. aircraft could suffer more damage than China’s if they attacked each other’s bases in the region, which would prevent U.S. air operation for a duration of time, said analysts.

According to Kelly Grieco, a senior fellow at the Stimson Center’s Reimagining U.S. Grand Strategy Program, attacks on U.S. bases in the Pacific region, including Japan could “prevent the U.S. Air Force from conducting fighter operations for about the first 12 days of a conflict from U.S. bases in Japan.”

Grieco continued, based on her own report published by the Stimson Center, that Chinese missiles could also take out runways and aerial refueling tankers, rendering them unusable for over a month at U.S. bases in Japan and for over half a week at U.S. military bases in Guam and other Pacific locations.

“It’s not possible to harden a runway or taxiway” that is exposed as an easy target to destroy, disabling aircraft from taking off, she said. This begs the question of whether it is worth investing in hardening facilities, she added.

The Hudson Institute report says within the 1,000 nautical miles of Taiwan, China has added 20 runways and 49 taxiways since the 2010s while the U.S. added one runway and one taxiway.

Unhardened airfields

Among U.S. air bases in the allied countries of Japan, the Philippines and South Korea, those in the Philippines are the least protected, Timothy Walton, one of the authors of the Hudson report, told VOA.

“In Japan, Kadena and Misawa Air Bases are the most fortified U.S. bases, while the remainder are largely unfortified,” said Walton, a senior fellow at Hudson’s Center for Defense Concepts and Technology.

“In the Republic of Korea, the two U.S. Air Force bases, Osan and Kunsan, are hardened. Airfields in the Philippines are unhardened,” he said.

Grieco said the U.S. would mostly rely on its bases in Japan, Guam and other Pacific locations as South Korea would “restrict the use of U.S. bases in its territory in a Taiwan contingency out of concern about North Korean aggression and to avoid a rupture with Beijing.”

U.S. Representative John Moolenaar, the chair of the House Select Committee on the Chinese Communist Party, Senator Marco Rubio, President-elect Donald Trump’s pick for secretary of state, and 13 other lawmakers underlined last year the importance of hardened shelters to protect against Chinese attacks.

In a letter sent to Air Force Secretary Frank Kendall and Navy Secretary Carlos Del Toro in May, they said, “U.S. bases in the region have almost no hardened aircraft shelters compared to Chinese military bases,” leading to U.S. air assets being “highly vulnerable to Chinese strikes.”

Aside from hardened shelters, analysts pointed to dispersing airfields as important.

Steven Rudder, a nonresident senior fellow at the Atlantic Council and former commanding general of U.S. Marine Corps Forces, Pacific, said, “When you look at the number of aircraft in the Asia Pacific, I am not sure that the ability to harden every single aircraft parking space would be as effective as a distributed force.”

Bruce Bennett, a senior defense researcher at Rand Corporation, said dispersing airfields are important against nuclear strikes.

Against conventional warhead missiles, shelters are “key to the protection,” said Bennett. “But if there’s a nuclear threat, you’ve got to have different airfields” as alternative locations to park and land aircraft and to provide logistic support such as fueling, maintenance and repair, he said.

Bennett added the disparity in the number of aircraft shelters between the China and U.S. seems to stem from U.S. air superiority.

“What the U.S. Air Force tends to perceive is that we’ve got the ability to deal with the Chinese air force in an air-to-air combat,” where China traditionally felt it would lose air-to-air combat against the U.S. and therefore wants to take U.S. aircraft on the ground before engaging in air while sheltering theirs heavily on the ground, Bennett said.

“The question becomes, as the Chinese aircraft get better and as they start fielding fifth-generation fighter, will the U.S. need the ability to attack Chinese airfields with conventional weapons? I don’t think the Defense Department has considered it as one of important tasks,” Bennett said.