The summit will be dedicated to mending transatlantic relations, as well as to fairer distribution of financial burdens in the alliance and the fight against terrorism.

The first summit to be held at the new NATO headquarters will also be the first time in Brussels for US President Donald Trump, who has called the EU capital a "hellhole" and NATO "obsolete".

Although he has retracted on the latter, the bitter aftertaste remains and the summit is seen by pundits as a chance to improve relations after the rough start.

Trump will be accompanied by his Slovenian-born wife Melania Trump, who will take part in the first spouse programme, which will also be attended by Cerar's partner Mojca Stropnik.

Unofficial information indicates that Stropnik is expected to speak with the US first lady and once again extend Slovenia's invitation for her to visit the country with her husband.

On Friday, Cerar is expected to meet Stoltenberg. The pair is expected to discuss the topics which will also be in the focus of the summit.

Cerar is expected to highlight the importance of stability in the Western Balkans and of the need to remain focused on the region also after Montenegro's joining NATO, which is expected in June.

In early March, Stoltenberg welcomed Slovenia's increase in defence spending as well as the country' participation in NATO missions. But he also added that he looked forward to further increases.

Allocating around 1% of its GDP for defence, Slovenia is still far below the 2% target, which places it among the members with the lowest defence spending.