Stoltenberg will be received by Prime Minister Marjan Šarec at the Brdo Estate for talks and lunch before viewing an exercise by the Slovenian Armed Forces Special Operations Unit.

The secretary-general will then travel to Ljubljana to visit the National Assembly for talks with Speaker Dejan Židan and to address MPs. He will wrap up the visit by meeting President Borut Pahor.

The talks are expected to focus on NATO's demand for increased defence spending. The allies committed to raise their defence expenditure to 2% of GDP by 2024.

Slovenia is to allocate 1% if GDP for defence this year, one of the lowest proportions among NATO members. The current plan is to increase the sum to 1.2% of GDP by 2024.

Defence Minister Karl Erjavec has indicated he would like defence spending to increase to 1.1% of GDP next year.

In an interview with the STA ahead of the visit, Stoltenberg called on Slovenia to do more to meet the agreed target, but he did welcome an increase in defence spending in real terms.

This will be Stoltenberg's second visit to the country since he took office in October 2014. He visited for the first time in July 2015.

The visit is part of a tour that will also take him to Serbia and Croatia.