JUNE 2025
Norms in New
Technological Domains
What’s Next for Japan and the United States in Cyberspace
By Koichiro Komiyama
This report is part of Strategic Japan, a CSIS Japan Chair initiative featuring analysis by Japan’s leading
foreign policy scholars on key regional and global challenges and the implications for the U.S.-Japan alliance.
Introduction
Cybersecurity and national security have become inseparably intertwined in recent years. Once
regarded as a global commons—an open and interconnected frontier—cyberspace has rapidly been
reframed both as the fth domain of warfare (the other four being land, sea, air, and outer space) and as
the front line of great power competition. In addition, cyberspace has proven to be far more centralized
than many initially believed. It is a space where just eight providers generate 65 percent of all internet
trac. A triadic competition—specically, the contest among democracies, authoritarian states, and
big tech companies—constantly arranges (and rearranges) cyberspace.
In February 2025, Japanese Prime Minister Shigeru Ishiba visited Washington, D.C., and held a summit
meeting with President Trump. On that occasion, the two leaders issued a joint statement, declaring
that they “intend to expand bilateral security cooperation in cyberspace by leveraging new technologies
such as articial intelligence and secure and resilient cloud services to deepen information-sharing.”
The statement positioned cyber as a core pillar of the U.S.-Japan alliance and signaled a willingness
to jointly confront emerging digital threats through shared technological and operational capacities.
Just as the U.S.-Japan security alliance remains an indispensable mechanism for regional stability, the
joint statement clearly reects both countries’ recognition that enhanced bilateral cyber cooperation is
essential for ensuring order and stability in an increasingly unstable cyberspace.
This white paper examines how Japan and the United States should pursue bilateral cooperation in
cyberspace within the framework of the current U.S.-Japan alliance, which remains one of the most
