"We are realistic, we know we will not be in NATO during the war," Zelensky said after meeting Dutch and Belgian Prime Ministers Mark Rutte and Alexander De Croo.

"But we want a very clear message that we will be in NATO after the war," Zelensky added.

Zelensky made a surprise visit to the Netherlands a day after meeting Nordic leaders in Finland to drum up support ahead of Ukraine's awaited counter-offensive against Russia.

"The most important thing is to deliver as quickly as possible what was promised to our soldiers," Zelensky told reporters.

"We hope that the Netherlands and our other partners will help as quickly as possible," Zelensky said.

The Netherlands has so far given or pledged 1.2 billion euros in military support to Ukraine.

This included 45 T-72 tanks, armoured personnel carriers and at least 100 Leopard 1 tanks, together with Denmark and Germany, as well as 14 Leopard 2 tanks together with Denmark.

It also included eight howitzers and 120 mm shells as well as two Patriot missile systems, 100 mobile air defence cannons and Stinger missiles among other weapons, the Dutch defence ministry said on its website.

Dutch instructors are also helping to train Ukrainian recruits along with other Western nations.

Zelensky was to visit a Dutch military base later on Thursday in central Netherlands to view equipment reserved for Ukraine.

Earlier in the day he visited the International Criminal Court, where he insisted on creating a special tribunal for Ukraine, rather than a so-called "hybrid court."