Leaders of NATO's 32 member states will gather in The Hague on June 24-25 for a critical summit dominated by debates over increased defence spending, Ukraine's membership bid and the geopolitical fallout from recent US strikes on Iran.
At a meeting on June 5 at NATO headquarters in Brussels, allied defence ministers agreed on the capability goals needed for the coming years.
Turkish President Recep Tayyip Erdogan, the main mediator of the conflict between Russia and Ukraine, will also attend the NATO summit.
The most contentious item expected to be formally adopted in The Hague is a US-backed proposal requiring member states to allocate at least 5 percent of their GDP to defence spending, a goal initially floated during Donald Trump's first presidency.
Currently, European allies spend an average of 1.9 percent of GDP on defence. Canada allocates around 1.4 percent, while the US spends approximately 3.5 percent.
Under a compromise formula proposed by NATO Secretary General Mark Rutte, 3.5 percent of the 5 percent target would be earmarked for direct military capabilities, including weapons, ammunition, training and forces, while the remaining 1.5 percent could cover general security investments and aid to Ukraine.
The initial aim is to reach the target by 2032. However, neither this potential adjustment nor Rutte's formula has garnered unanimous support among allies.
Five percent defence spending fallout
Opposition within the alliance Spain has emerged as the clearest opponent of the proposed target. With the lowest defence spending in the alliance at 1.3 percent of GDP, it is seeking an exemption from the new benchmark.
Spanish Prime Minister Pedro Sanchez has reportedly sent a letter to Rutte urging that the summit declaration either make the spending target voluntary or explicitly exclude Spain from the 5 percent requirement.
Rutte has justified the 5 percent goal largely on the basis of growing threats from Russia.
However, threat perception varies across the alliance, and many governments face domestic resistance to increased military spending due to rising national debt and public scepticism.
Sanchez argued that the 5 percent goal does not align with Spain's strategic vision and is not necessary for fulfilling NATO obligations.
"Spain thinks they can achieve those targets on a percentage of 2.1 percent of gross domestic product," Rutte told reporters Monday ahead of the summit.
"NATO is absolutely convinced Spain will have to spend 3.5 percent to get there."
On Monday, Slovak Prime Minister Robert Fico joined Spain's calls.
Fico said that Slovakia reserves the right to decide how fast and by how much it will increase its defence budget, arguing that Bratislava can fulfil its NATO commitments without hitting the 5 percent mark.
The key challenge for Rutte is to persuade all allies to set aside their objections before leaders' discussions, when Dutch King Willem-Alexander will host an official dinner for the leaders.
Ukraine-Russia war
Zelenskyy, EU and Asia-Pacific leaders to attend a dinner, hosted by the Dutch King, which will bring together several key figures beyond NATO's core membership, including Ukrainian President Volodymyr Zelenskyy, European Council President Antonio Costa, European Commission President Ursula von der Leyen and leaders from Asia-Pacific partners such as Australia, New Zealand, South Korea and Japan.
Zelenskyy's invitation is being interpreted as a symbolic gesture of support.
The summit declaration is expected to include a reference to NATO's "sovereign commitments" to Ukraine's security.
While former NATO Secretary General Jens Stoltenberg frequently stated that Ukraine could join NATO "after the war ends," Rutte clarified that "no promises have been made."
However, he reaffirmed Monday that Ukraine's path to NATO membership, deemed "irreversible" at last year's Washington summit, remains unchanged.
Meanwhile, US President Donald Trump previously said that Ukraine’s NATO membership will never happen and claimed the issue was the root cause of the war with Russia.
Middle East conflict
Beyond the debate over numbers, the summit risks being overshadowed by a more urgent geopolitical development: US military strikes on Iranian nuclear facilities and Iran's counterattack targeting US bases in Qatar and Iraq.
Just days before the summit, the US operation reignited fears of a broader conflict in the Middle East, stirring concerns among European allies.
The crisis has prompted renewed discussions about missile defence and counterterrorism, which are expected to be on the agenda alongside defence spending.
However, the broader concern is whether the Iran conflict will derail the summit's core focus and signal a distracted alliance.
Experts note that the Iran issue represents an unpredictable and potentially destabilising factor for the summit. With Washington's focus increasingly shifting from Europe and Russia toward the Middle East and Asia, European allies fear losing political momentum and unity against Russia.
Addressing the Iran issue just days after the US bombed Iranian nuclear facilities, the NATO chief reaffirmed on Monday the alliance's longstanding position against nuclear proliferation.
