Defense chiefs from Japan, Australia, the Philippines and the U.S. have agreed to further expand military cooperation, and — although “China” was not uttered by the four officials during their first-ever joint news conference Thursday in Hawaii — Beijing’s growing regional assertiveness was clearly at the top of their agenda.

At the meetings, which saw U.S. Secretary of Defense Lloyd Austin host Japanese Defense Minister Minoru Kihara, Australian defense chief Richard Marles and Philippine Defense Secretary Gilberto Teodoro in Honolulu for a series of bilateral, trilateral and quadrilateral engagements, the four reiterated the need for deepening ties and building up interoperability.

Austin said that the four-country grouping would undertake more joint maritime military exercises, while the U.S., Japan and Australia would also provide even greater security assistance to the Philippines amid a territorial row with China.