WASHINGTON - The US Defense Department is moving forward to expand its international defense partnerships in cyberspace, starting from traditional allies, a senior defense official said Tuesday at a cyber defense forum.

Cyberspace is a novel arena for defense partnerships, said Steven Schleien, the department's principal director for cyber policy, adding that the department has started with its traditional treaty allies.

Schleien spoke at Georgetown University's second annual International Engagement on Cyber in the capital where experts from Washington, the Netherlands and Russia addressed issues in cyberspace.

Officials are working toward long-term goals of collective cyber self-defense and deterrence, Schleien said.

The department started in accordance with President Barack Obama's international cyberspace strategy, released in May 2011, which said that "hostile acts in cyberspace could compel actions under our mutual defense treaties."

Defense officials worked with its allies and NATO staff during the 2010 Lisbon Summit, Schleien said, to bring all NATO networks, civilian and military, under the NATO Cyber Incident Response Center, which is expected to be complete later this year.

Officials are also starting to talk with the Japanese, South Korean and New Zealand defense ministries about cyber security, while working closely with the British and Australian ministries "to talk about a whole spectrum of cyber interoperability."

The US Department of Defense unveiled in July, 2011 its strategy for protecting the US government, military and private firms from cyber attacks, defining cyberspace as a domain similar to air, land, maritime and space in its operations.