Rupel, who was Slovenia's foreign minister when the country joined NATO on 29 March 2004, says that NATO was Europe's only serious defence against the collapse of the Schengen, terrorism, cyberattacks and other threats.

Without NATO, Europe would be unprotected and Slovenia could not have survived as an independent and decent country, he believes. "Some people in Europe forget that the Americans have saved us in three wars: the first, the second and the Cold War."

The US did pursue an isolationist policy at times, something that can also be seen today, albeit "in mild form". "I believe that Europe is more at fault for the tensions than the US."

"Of course the US has its interests in Asia-Pacific as well. But I believe there are more things that we have in common than divide us."

Brexit and US President Donald Trump's warnings about defence spending are "putting all of us in danger", Rupel believes. He also worries about the future of Europe as it has been alternating between the liberal and the socialist visions.

He is critical of the Left for having a problem with NATO. He believes that the opposition party wants to return to socialism and the Non-Aligned Movement.

"They would not have had a problem if we weren't a member of NATO. In truth, our leftists have such power that they hinder the development of the military. Maybe they want to get NATO to expel us."

Rupel says that Slovenia was the only former socialist country, apart from Serbia, which had wanted to avoid NATO membership.

"By this I mean the initiative of former UN Ambassador Danilo Türk that Slovenia become a member of the anti-NATO New Agenda Coalition. This was prevented in 1998 by [the then Prime Minister Janez] Drnovšek. But we did have to wait for an invitation until after 9/11 when the US opened the door wide."

Touching on the European defence union, Rupel says that closer defence cooperation will be needed within the EU. However, this must not be a substitute for NATO.

The EU must defend its borders, especially in the east and the south, he underlines. The bloc will also have to address the issue of migration.

"Large investments will be needed to address the issue and to defend the borders, which will affect the comfortable way of life in Europe."

Asked about the relations between NATO and Russia, Rupel says that these were excellent following the 2001 meeting of George W. Bush and Vladimir Putin in Slovenia's Brdo pri Kranju.

"But then Putin made some strategic mistakes reminiscent of the Soviet tradition. I'm not sure what our Slavic cousins are doing in Iran and Syria."

"Ukraine, of course is the biggest problem. NATO should not have given in to Russian - and German? - pressure. The same goes for Georgia," Rupel has told the STA in the e-mail interview.