In a significant development, NATO allies are nearing consensus on a new defence spending target, potentially setting it at 5% of GDP. This marked increase from the existing mandatory target of 2% has garnered support, notably from U.S. Secretary of State Marco Rubio, who advocated for the higher spending level during his recent visit to Brussels.

NATO Secretary-General Mark Rutte has also endorsed this ambitious target, highlighting the expanding discourse around what constitutes defence spending.

Currently, NATO measures its members' spending through a framework that includes military equipment purchases, infrastructure projects, overseas operations, soldiers' salaries, and pensions.

However, as European capitals grapple with the existing defence spending gap with the United States, estimated at €307 billion, there is increasing pressure to redefine acceptable expenditures.

This initiative is motivated by concerns that the U.S. may reconsider its commitment to NATO should European allies fail to meet spending expectations.

The proposal to include a broader array of expenditures under the 'defence' umbrella is gaining traction among member states.

Activities that could soon be counted as defence spending might encompass military assistance to Ukraine, infrastructure developments deemed critical for military readiness, and the civilian development of dual-use technologies that enhance national security.

The discussions surrounding this redefinition are taking place in light of the upcoming NATO summit scheduled for June in The Hague.

European allies are examining options to expand traditional defence spending while integrating a broader security-related spending target, with Rutte's plan suggesting a split that allocates 3.5% to conventional defence and an additional 1.5% to expanded security spending.

This shift in approach comes as Europe's largest economies, namely Germany and France, advocate for an emphasis on quality spending rather than merely increasing expenditure levels.

Germany, in particular, has dedicated substantial resources to military enhancement in response to NATO's current targets, but remains focused on the efficacy of such investments.

Under Rutte's strategy, the emphasis on broadening expenditures would not only push European countries to enhance their defence capabilities but also to consider contributions that align with the strategic needs of NATO amidst ongoing global tensions.

The proposed new definitions of 'responsibility sharing' could also lead to initiatives supporting Ukraine and efforts to reduce reliance on Russian energy supplies being counted towards national spending goals.

Such a change could serve to elevate spending levels for 13 NATO allies above the projected 4% mark, although it might exclude key players like Germany and France.

With Russia potentially increasing its spending to 6.7% of GDP and China targeting 7.2% this year, the adjustment to NATO's spending formulas may help align European military capabilities more closely with those of these geopolitical adversaries.

However, NATO diplomats acknowledge that striking a balance between ambitious spending goals and the realities of national fiscal constraints will require careful negotiation and time to implement.

As European leaders prepare for the pivotal June summit, they are mindful of the past tumult of the 2018 Brussels meeting, which saw public disputes over defence commitments, particularly involving then-President Trump's criticisms of Germany.

The current discussions emphasize the importance of unity and strategic planning as NATO seeks to navigate an increasingly complex security landscape.