British army reservists will be expected to be “part time regulars” as the military tries to slash costs by cutting the number of full-time soldiers, defense officials said on Thursday.

The Ministry of Defense plans to reduce its regular army to 82,000 from 102,000 by 2020 and make up for the shortfall by doubling trained reserve numbers to 30,000 as part of Britain’s efforts to tackle its big budget deficit.

Experts say the move is a good idea given the army’s need for specialist skills available in the civilian workplace, such as cyber, medical and intelligence, but that it may be difficult to get employers and potential reservists to commit to the extra responsibilities required of them under the new plan.

“This is a fundamental change in role requiring a fundamental cultural shift in approach: a new deal for reserves,” Defense Secretary Philip Hammond said at the Royal United Services Institute (RUSI) defence think tank, announcing a 1.8 billion ($2.8 billion) pound investment in reserve forces over the next decade.

“A higher quality reserve that will have a far greater expectation of use and whose level of contribution will be planned, programmed and properly resourced,” he added.

Some battalions will be reinforced through a permanent partnership with reserve units, while less complex tasks could mainly be handled by reservists augmented by regular forces, Hammond said, adding that he planned a major reservist recruitment drive.

Britain’s reserve forces have declined over the years and only form a small part of current military capability.

“Using reserves does make sense in a fast changing world when you want to make use of a wide range of skills which are often held by people who do not want to commit to the army full time,” said Malcolm Chalmers, research director at RUSI.

“How the army will persuade employers to let reservists go for several months or enlist reservists in the first place is the big question,” he added.