As part of the one-day visit, Stoltenberg will meet Slovenian Prime Minister Miro Cerar, President Borut Pahor and parliamentary Speaker Milan Brglez, and visit the NATO Multinational Centre of Excellence for Mountain Warfare in Poljče.

According to the PM's office, Cerar and Stoltenberg will focus on the topics for the next NATO summit in Warsaw, which will discuss future cooperation among the allies, and Slovenia's commitments to NATO.

The two officials are also expected to discuss an enlargement of NATO to the Western Balkans, in particular the candidacy of Montenegro, which is currently the best prepared country for NATO membership from the region.

Cerar and Stoltenberg are furthermore expected to talk about the challenges coming from East Europe and southern Mediterranean as well as Slovenia's participation in NATO peace-keeping operations and cooperation between NATO and the EU.

This will be the first visit by a NATO secretary general to Slovenia since January 2014. Cerar already met Stoltenberg, who served as the prime minister of Norway between 2005 and 2013, in his current capacity in Brussels last November.

On the occasion, the secretary general praised Slovenia's contribution to NATO operations, especially in Kosovo, while also pointing to the need to increase spending for defence, especially for investments.

NATO published statistics in June showing that Slovenia ranks among the third of NATO member states with the lowest defence expenditures as share of GDP. In 2014 the country earmarked 1% of its GDP, which is the least since its accession to the alliance in 2004.

Slovenia gave the highest proportion of its 2014 defence budget for personnel expenditures at 82.3%, while ranking the lowest among all member states by the proportion it earmarked for investment in armament and equipment, at 0.7% of Slovenia's defence expenditure.

Defence Minister Andreja Katič announced at a recent NATO ministerial an end to cost-cutting and gradual increase in Slovenia's defence budget. "Slovenia is aware that all of us need to meet the commitments," she said, announcing the increase in defence budget by 0.04 percentage points of GDP a year.

NATO member states agreed at the summit in Wales last year to gradually increase the share of defence expenditure over the next decade to 2% of GDP, provided their fiscal position allowed that. Projections for this year show the countries are not yet nearing the goal.