According to the Times, the measures are part of a wider range of strategies to hit back at an increasingly assertive Russia -- accused of interfering with US elections, cyberattacks on Western targets, and poisoning a former spy on UK soil -- without resorting to a full-blown nuclear attack.

"If they sank our aircraft carrier with a nuclear-tipped torpedo, what is our response? There's nothing between sinking their submarine and dropping a nuclear weapon on northern Kamchatka", one senior source told the Times.

"This is why cyber is so important; you can go on the offensive and turn off the lights in Moscow to tell them that they are not doing the right things."

Military planners are looking for options if Russian president Vladimir Putin tests NATO's resolve by seizing small islands belonging to Estonia, taking control of Libya's oil reserves, or using "irregular forces" to attack troops, according to the report.