Jens Stoltenberg, NATO Secretary General, told the Belgrade Security Forum gathering “Leadership for a Secure Region” on Monday that it was necessary to expect the unpredictable and unforeseeable events, the Beta news agency reported.

He added it was (now) more challenging to differentiate between war and peace, stability and conflict.

“We have to understand the fact that we live in the time of the hackers’ wars, hybrid wars,” Stoltenberg said, taking part in the discussion together with Serbia’s President Aleksandar Vucic.

Earlier the two attended the beginning of the intentional disaster relief exercise “Serbia 2018” held in Belgrade’s suburb of Mladenovac.

NATO chief mentioned the Arab Spring, the Russian annexation of Crimea and the emergence of the Islamic State as events only a few could predict and that’s why “we have to be prepared and react quickly.”

He added that NATO raised its Hi-tech, combat and intelligence community readiness.

Speaking about the Balkans, Stoltenberg said he was worried about the return of the nationalistic rhetoric.

“Brussels cannot solve the regional problems. It can help. People who live here should resolve all the issues, and I call for peace, and not to go back to nationalistic rhetoric,” he said, adding that despite other problems, the regional instability was a high-security risk for the whole of Europe and NATO.

Vucic said Serbia would do everything to avoid conflicts and preserve peace and stability in the region.

“We’ll do our best to continue the dialogue with the Pristina's Albanians, to improve relations with new Bosnia’s leaders and there is no doubt that we will have a better relationship with Croatia as much as we can contribute to it,” Vucic told the gathering.

He said Serbia would also do everything possible to avoid causing a headache to the great powers, but most of all to its people.

“We know what was done to us, what we did to others and that’s why we should not repeat the mistakes from the past, but take care of the future.”