The Pentagon is contemplating an aggressive approach to defending its computer systems that includes preemptive actions such as knocking out parts of an adversary’s computer network overseas — but it is still wrestling with how to pursue the strategy legally.

The department is developing a range of weapons capabilities, including tools that would allow “attack and exploitation of adversary information systems’’ and that can “deceive, deny, disrupt, degrade, and destroy’’ information and information systems, according to Defense Department budget documents.

But officials are reluctant to use the tools until questions of international law and technical feasibility are resolved, and that has proved to be a major challenge for policy makers. Government lawyers and some officials question whether the Pentagon could take such action without violating international law or other countries’ sovereignty.