WASHINGTON - The United States said Thursday that attacks in space would invoke its defense treaty with Japan and announced the deployment of a more agile Marine unit on its ally’s soil as alarm grows over China. Weeks after unveiling plans to ramp up security spending, Japan sent its defense and foreign ministers to Washington where the two countries issued a statement vowing to “modernize the alliance in order to address the increasingly severe security environment.” The talks come two days before a visit by Prime Minister Fumio Kishida, who is touring Group of Seven nations to kick off Japan’s leadership year of the elite club and earlier Wednesday in London also boosted defense ties with Britain. As China makes rapid advances in satellites, the United States and Japan warned in their statement that “attacks to, from or within space present a clear challenge to the security of the alliance” that could invoke Article Five of their mutual defense treaty, which considers an attack on one an attack on both. The talks finalized a plan by the United States to send a so-called Marine Littoral Regiment, a more agile unit that can operate defenses both by sea and air, to Okinawa, the southern Japanese island strategically close to Taiwan. US Defense Secretary Lloyd Austin said the unit would be in place by 2025 from a reorganization of an existing artillery regiment.