US Secretary of State Antony Blinken, Defense Secretary Lloyd Austin and their Japanese counterparts "reiterated their strong objections to the PRC's unlawful maritime claims, militarization of reclaimed features, and threatening and provocative activities in the South China Sea," a joint statement said.

China's "destabilizing actions in this region include unsafe encounters at sea and in the air, efforts to disrupt other countries' offshore resources exploitation, as well as the dangerous use of Coast Guard and maritime militia vessels," the communique added.

They accused China of "intensifying attempts to unilaterally change the status quo by force or coercion in the East China Sea" and that Chinese "foreign policy seeks to reshape the international order for its own benefit at the expense of others".

In addition they expressed concern about China's "ongoing and rapid expansion of its nuclear weapons arsenal, which continues without any transparency regarding its intent and which the PRC (People's Republic of China) refuses to acknowledge, despite publicly available evidence."

The statement also "highlighted with concern Russia's growing and provocative strategic military cooperation with the PRC, including through joint operations and drills in the vicinity of Japan, and the PRC's support for Russia's defense industrial base."

They also "strongly condemned deepening Russia-North Korea cooperation, exemplified by Russia's procurement of ballistic missiles and other materiel from North Korea in direct violation of UNSCRs (UN Security Council resolutions) for use against Ukraine."

Blinken and Austin's talks involving Japanese Foreign Minister Yoko Kamikawa and Defence Minister Minoru Kihara were aimed at boosting military cooperation between Tokyo and Washington in response to concern about China's growing assertiveness in the region.