The head of Nato has defended the decision to allow alliance members to include pensions as part of their calculations to hit the 2% GDP expenditure target.
During a two-day defence ministers meeting in Brussels, Secretary General Jens Stoltenberg said he expects eight members to meet the defence spending baseline this year.
Britain currently only just reaches the Nato target - with a total spend of GDP on defence topping 2.1% - but critics have claimed this figure is inflated by items such as pensions.
When quizzed by the Press Association on whether the inclusion of pensions is the right thing to do, he said it is important to have a standardised measure across all 29 members, adding the process is one that has been used for decades.
"Pensions are part of the personnel costs. If you have soldiers you also have to pay their salaries and their pensions," Mr Stoltenberg said.
"This is an established way to measure defence spending which provides us with a measure that can provide consistent and comparable figures from all Nato allies."
Mr Stoltenberg earlier told reporters that to "keep our nations safe, we need more defence spending, investment in key capabilities, and forces for Nato missions and operations".
Working to turn around years of military cuts, after Nato nations slashed defence spending following the end of the Cold War, since 2014 there has been a drive to boost budgets.
Mr Stoltenberg said it is important to deliver on the decision for members to meet the 2% target, set four years ago, and that so far there has been a "good start" to achieving this.
"More and more nations and Nato allies are moving towards 2%, and more and more allies are reaching the 2% target," he said.
"In 2014 when we made the decision only three countries were at 2% or above.
"This year we expect eight, and according to national plans that allies have presented at least 15 nations will be at 2% by 2024.
"This is a good start, this is the first year with what we call national plans, and we will urge allies to do more and revise national plans, and improve defence spending.
"After three years we have really turned a corner - after years of decline, Nato allies have started to increase defence spending again.
"Now, the focus is on delivering what we have promised."
Pressed on whether he thinks reaching the stage where all members meet the 2% target is achievable, he told the Press Association that it "absolutely" is, and there is a "willingness" to continue the increase.
"Firstly... this is only the start, and after three years we have seen for the first time, three consecutive years with increase in defence spending across Europe and Canada," he said.
"Second, according to the national plans this will continue, but I will continue to urge for more - meaning revised national plans, (and) stronger commitments."
Last month the head of the British Army, General Sir Nick Carter, warned how Russia has an "eye-watering" capability that the UK would struggle to match without a bigger defence budget.
Asked for his thoughts on this, Mr Stoltenberg said Britain "provides many important capabilities" to the alliance.
"The UK is one of the Nato allies that meets our 2% guideline, and the UK has met it for many years, and the UK is leading by example by spending 2% and more on defence," he added.
His comments come in the wake of analysis by the International Institute for Strategic Studies, which suggested the UK fell just short of the 2% target.
Findings published by the think tank suggest UK spending in 2017 was 50.7 billion US dollars (£36.4 billion) - the equivalent of 1.98% of GDP - something the Ministry of Defence has rejected.