The Defense Ministry has identified a virus inside one of its computer networks, in an instance of a cyber attack that penetrated its security defenses, Israel’s Channel 2 news reported on Tuesday night.

Israel’s security establishment battles intermittent cyber-attacks, the report said, but in this case the virus succeeded in entering one of the ministry’s computer systems. There was no indication of any damage the virus might have caused.

The ministry was now investigating the attack, the report added. The Israeli security establishment relentlessly refines its defenses against cyber-attack, the report quoted security officials as saying.

Iran has accused Israel and the United States of responsibility for planting various computer viruses in its computer networks, including Stuxnet and Flame, as part of efforts to sabotage its nuclear program. Israel has issued no formal responses to such accusations.