The U.S. and Australia reached an agreement to expand the U.S. military footprint on the southern continent, as both countries bolster defense ties to respond to an increasingly assertive China.

The changes include more frequent and longer visits of U.S. submarines to Australia, a regular rotation of U.S. Army watercraft and collaborating on guided missile production, the nations’ defense ministers announced on Saturday in Brisbane.

Australian Defense Minister Richard Marles said the U.S.-Australia relationship "has never been in better shape than it is right now” as he reeled off a list of efforts to enhance cooperation. Foreign Minister Penny Wong called Washington the country’s "closest strategic partner.”