Japan and the United States are expected to agree in bilateral security talks next week to strengthen their defenses against cyberattacks, a diplomatic source said Saturday, apparently with North Korea and China in mind.

Expanded cooperation is expected to be stipulated in a joint statement to be issued after a "two-plus-two" security meeting of their foreign and defense chiefs in Washington on Thursday, the source said.

As cyberattacks pose a serious threat to national security, Japan and the United States aim to bolster measures to prevent any leak of classified information, including that on state-of-the-art weapons, and to protect essential communication and transport infrastructure, the source said.