CAPABILITY GAP

But he will warn that defence spending among the allies is increasingly uneven, not just between North America and Europe, but also among European allies, as some cut defence spending more than others.

If this capability gap continues to grow, it could limit the allies’ ability to work together and risk weakening political support for NATO in the United States.

While total defence spending by NATO members has been going down in recent years, the defence spending of new and emerging powers has been going up.

If those trends continue, NATO’s military capacity and political credibility could be put at risk, Rasmussen will say.

The rise of emerging powers could create a growing gap between their capacity to act and exert influence on the international stage and NATO’s ability to do so, he will say.

Rasmussen will not name any countries but China boosted military spending by 11 percent last year, continuing a near-unbroken string of double-digit rises across two decades.

Defence spending by NATO’s military superpower, the United States, is set to be $633 billion this year.

That dwarfs China’s official military spending, $110 billion in 2012, although many foreign experts believe Beijing’s public budget undercounts its real spending on military modernisation.