NATO allies will need to spend much closer to 3% of their gross domestic product (GDP) on their militaries to implement the alliance's new defense plans, a NATO top military official said Monday, as costs will surpass the alliance's existing 2% target.

"The overall percentage that is necessary to make the new plans executable is much closer to 3% of GDP than it is to 2%," the Chair of NATO's Military Committee Rob Bauer said in Brussels.

"I expect that under the new (Donald) Trump administration (in the U.S.), there will be a much more intense discussion about how much more Europe and Canada need to spend, and that is a healthy and valid discussion to be had."