The foreign and defense chiefs of Japan and the United States confirmed on Friday for the first time that Article 5 of the two countries’ security treaty, which sets out Washington’s obligations to defend territories under Tokyo’s jurisdiction, could apply to cyberattacks against Japan.

This was clarified in a joint statement adopted at so-called two-plus-two security talks held among the ministers in Washington the same day.

The officials affirmed that “a cyberattack could, in certain circumstances, constitute an armed attack for the purpose of Article 5” of the security treaty, the statement said, adding that a decision as to whether a cyberattack would be covered by the article will be made “on a case-by-case basis, and through close consultations” between the two countries.

While refraining from citing specific countries, the statement implicitly expressed concerns over rapid technological progress made by China and Russia in the new fields.

“Malicious cyber activity presents an increasing threat to the security and prosperity of both the United States and Japan,” it said.

Japan-U.S. collaboration in cross-domain operations involving the conventional air, ground and maritime defense fields, and the new domains, is one of the “core objectives” to advance the two nations’ defense relationship, the statement added.

It also said the officials highlighted space, cyberspace and the electromagnetic spectrum as priority areas to better prepare the alliance for cross-domain operations.

Friday’s two-plus-two meeting was the first since August 2017. Foreign Minister Taro Kono and Defense Minister Takeshi Iwaya took part, while the U.S. side was made up of Secretary of State Mike Pompeo and Acting Defense Secretary Patrick Shanahan.

At a joint news conference after the meeting, Pompeo criticized China, which has been boosting activities in cyberspace and other fields. Pompeo said that he and Shanahan shared their concerns with Japan that “geopolitical competition and coercive attempts to undermine international rules, norms and institutions — especially from China — present challenges to the alliance and to continued peace, stability and prosperity in the Indo-Pacific.”

Kono said that Japan and the United States will further strengthen their alliance by enhancing bilateral cooperation, including in the new fields.

The defense cooperation guidelines that were revised in April 2015 only said that “the United States will provide appropriate support to Japan” in dealing with cyberattacks against the Asian ally.

This time, the two countries more clearly showed their intention to work together by saying that Article 5 of the security treaty could apply to cyberattacks against Japan.

Beyond the cyber domain, the two-plus-two joint statement also expressed the ministers’ “serious concern” over “unilateral coercive attempts to alter the status quo” in the East China Sea and the South China Sea — a not-so-oblique reference to China.

Tokyo and Washington also reconfirmed that the Japanese-administered Senkaku Islands in the East China Sea are covered by Article 5 of the security treaty. The islands are claimed by China and Taiwan.

The joint statement stressed a policy of supporting Southeast Asian countries in a bid to realize a free and open Indo-Pacific region.

“The Japan-U.S. alliance is now the cornerstone of peace, security and prosperity of the entire Indo-Pacific region,” Kono said. “Both Japan and the United States will conduct joint trainings and capability buildings and others with partner countries in order to jointly expand their presence in the region.”

Speaking at the same joint news conference after the meeting, Iwaya requested cooperation from the United States in investigating the crash of an F-35A fighter in the Pacific during an Air Self-Defense Force exercise earlier this month.

Despite the accident, Shanahan expressed appreciation for Japan’s continued procurement of F-35s and other U.S. assets as part of efforts to promote interoperability.

The top officials welcomed diplomatic efforts by the administration of U.S. President Donald Trump “to achieve the final, fully verified denuclearization of the Korean Peninsula.”

They stressed the need to realize at an early time the relocation of U.S. Marine Corps Air Station Futenma in the densely populated city of Ginowan, Okinawa Prefecture, to the Henoko coastal district of Nago within the prefecture. The plan is “the only solution” that avoids the continued use of the Futenma base, they said in the statement.

In an apparent reference to a case in which a U.S. Navy sailor allegedly stabbed a Japanese woman to death in the Okinawa town of Chatan earlier this month, Kono said it is necessary to reduce the burden on local residents by moving step by step to prevent accidents and other incidents involving U.S. servicemen in Okinawa and deal with issues related to the bilateral status of forces agreement.