"We reaffirm our unwavering commitment to collective defense, enshrined in Article 5 of the Washington Treaty - an attack on one [member state] is an attack on all," the summit's final document states.

All 32 allies also committed in the summit declaration to increase defense spending to 5% of GDP by 2035, as requested by US President Donald Trump.

Until now, NATO member states had committed to spending at least 2% of their GDP on defense, an agreement reached back in 2014 in Wales in response to Russia's initial invasion of Ukraine.

Over the past decade, two-thirds of member states have achieved this goal, and NATO Secretary General Mark Rutte has expressed confidence that the rest will finally do so this year.

However, with growing concerns that Russia could decide on a direct confrontation with NATO in the coming years, and bowing to pressure from Trump, the alliance's member states have agreed to more than double their defense spending.

According to the agreement reached, total defense spending is divided into two parts, with 3.5% of GDP allocated to direct defense spending, and another 1.5% allocated to defense-related infrastructure facilities.

The summit's final document recognized Russia as a"long-term threat" to collective security, and reiterated"long-term" support for Ukraine in its fight against Moscow's aggression.

The alliance's member states have declared that they are"united in confronting the major security threats (..), particularly the long-term threat posed to Euro-Atlantic security by Russia," the summit declaration said.

"Allies reaffirm their long-standing sovereign commitment to support Ukraine, whose security enhances our own," NATO leaders said.