TOKYO -- A group of lawmakers in Japan's ruling party on Thursday recommended that Japan and the U.S. revise their defense guidelines to focus on potential flashpoints involving China, particularly Taiwan and the South China Sea.

The guidelines set out the respective roles and missions of Japan's Self-Defense Forces and the U.S. military in the alliance, and how the two should work together.

The document was first drafted in 1978, during the Cold War, when an invasion of Hokkaido by the Soviet Union was seen as the main threat scenario. It has been revised only twice since then: in 1997, as North Korean ballistic missile tests brought the prospect of a Korean Peninsula conflict to the fore, and in 2015, when Japan passed legislation allowing limited exercise of the right to collective self-defense.

This proposed third update would put the Taiwan Strait in the spotlight, and emphasize preparing to deal with China and its military expansion.

The proposal by the Liberal Democratic Party's Foreign Affairs Division urged the government to consider how to evacuate Japanese nationals in the event of a conflict in the Taiwan Strait.

"The U.S. is focused completely on China and Taiwan," division chief Masahisa Sato, who is a former SDF colonel and considered to be a China hawk in the party, told Nikkei. "What will we do if something happens?"

The change would underline a shift in emphasis for defense cooperation between the two allies after Japanese Prime Minister Yoshihide Suga and U.S. President Joe Biden mentioned Taiwan in a joint post-summit statement in April for the first time since 1969.

Taiwan sits only about 110 km away from Yonaguni, Japan's westernmost inhabited island, and is also close to the Japan-administered Senkaku Islands, which are claimed by China as the Diaoyu and have seen repeated incursions by Chinese vessels in surrounding waters.

Sato pointed to integrated air and missile defense -- systems to intercept threats such as cruise missiles and fighter jets -- as a priority for U.S.-Japan cooperation. Proposals include detecting missiles with unmanned drones and launching a fleet of low-orbit satellites for tracking.

Beijing is said to have more than 2,000 midrange missiles. "China outclasses the U.S. in terms of missile firepower around Taiwan," a senior Defense Ministry official said.

The Biden administration's proposed budget for the fiscal year ending September 2022 calls for stepping up development of midrange land-based missiles.

To counter China's "anti-access/area denial" strategy, the U.S. envisions its own network of missiles stretching from Okinawa to the Philippines. Missile batteries could be installed at American military facilities in Japan, which would enhance the alliance's deterrence capabilities but also make the sites potential targets for Beijing.

Troops participate in joint exercises held by the U.S., Japan and France in southern Japan.   © Kyodo

Because forces from the continental U.S. would take up to three weeks to arrive in the event of a Taiwan conflict, American forces in Japan would initially serve as the front line. The SDF would likely play a support role in such a scenario, resupplying fuel and food and providing transportation.

Sato also called for Japan to participate in freedom of navigation operations in the South China Sea, which the U.S. has been conducting in response to Chinese military expansion there.

"It's a sea lane for crude oil shipments to Japan," he said. "The SDF should be involved in freedom of navigation operations and pave the way for ensuring the security of private vessels."

It has also been argued that protecting Japanese nationals and Americans living in Japan should be written explicitly into the guidelines, which are now limited to discussing the role of U.S. forces in responding to an armed attack. While this responsibility is now handled by the Japanese government and local authorities, help from American troops may be needed in some circumstances.

Washington and Tokyo are slated to hold a two-plus-two dialogue of foreign and defense ministers as early as this year. The two sides are expected to discuss whether the guidelines need updating, along with bolstering deterrence against China.