Stoltenberg called on Bulgaria to continue investing in military equipment, because NATO must be able to protect any ally and a direct threat against allies in the alliance was witnessed.

A very good synergy between military and civilian infrastructure is possible. A second bridge over the Danube near Ruse could be of strategic importance. "If we include this investment, I think we will meet the target of 2% of the country's GDP on defense expenditures," Petkov explained.