NATO Secretary General Mark Rutte is due to meet US President Donald Trump at the White House on Wednesday.
The talks are set to focus on Washington's expectations ahead of next month's alliance summit, particularly US demands for a rapid expansion of European defence capabilities.
The NATO summit is scheduled to take place in Ankara on July 7-8 and will bring together the leaders of the alliance's 32 member states. Ukrainian President Volodymyr Zelensky has been invited as a guest.
Rutte and Trump are also expected to discuss growing tensions within the alliance following a lack of support from NATO allies for the US military campaign against Iran.
Senior US officials, including Defense Secretary Pete Hegseth and Secretary of State Marco Rubio, have described allies' positions as "shameful" and signalled a possible reassessment of Washington's relationship with NATO.
For Rutte, the meeting presents an opportunity to ease tensions ahead of the summit and reduce the risk of a public confrontation between Trump and other alliance leaders.
A key question is what commitments European allies and Canada might be prepared to offer in order to satisfy US demands.
