The decision to bundle peacekeeping costs in with defence spending has been described as "little more than creative accounting" by UKIP defence spokesman Mike Hookem MEP.
Mr Hookem said the move was "another go at trying to cover up defence cuts by fudging the figures.
"They tried to make up the 2% target with foreign aid and with the military pensions and now it's the turn of peacekeeping. Our view is that the defence budget should be spent on troops, equipment and essential care such as decent housing and healthcare for personnel and their families. Anything else is an insult to the Armed Forces and the voters' intelligence.
"With the potential porous border for IS if Greece can't pay its public sector workers, NATO troops may be needed at the front line of the war against extremists and Britain must not be caught napping."