Croatia is losing a town of 15,000 inhabitants annually, for Croatia this is an existential issue, Plenkovic says in an interview he granted in Paris where, on Tuesday, he talked with French President Emannuel Macron.
"Thanks to tourism, that problem is smaller in Dalmatia but in eastern Croatia, due to population ageing and a lack of new jobs, people are leaving to build their future in other European regions," he says, adding that "populists get the most votes in eastern Croatia."
Asked if freedom of movement should be restricted to curb the problem, Plenkovic answers in the negative, saying that bringing freedom of movement into question would mean "touching the backbone of the European project."
"New member states must continue to utilise European aid in order to catch up with more developed ones and reduce the social gap. We must also have a catalogue of public policies for demographic revitalisation which have been successful in countries faced with the same problems," he says and mentions the Croatian government's tax breaks for young people.
"I personally insisted that the European Union deal with this issue because the dissatisfaction of people is fertile ground for the development of populism."
Plenkovic also talks about Croatia's bid to join the Schengen Area which, according to Le Monde, is opposed by some countries, including France.
"Juncker's Commission said that technically speaking, Croatia is prepared. I don't want to talk dates. With another two members (Bulgaria and Romania) in the Schengen waiting room, that would be too optimistic, but you should know that we have already absorbed €271 million in European funds to build our capacity to join Schengen. That's a lot for a country of our size."
As for the migration issue, Plenkovic says the EU must reach a consensus on sharing the migrant burden.
"A consensus is necessary because everyone doesn't have the same geography. Malta, Italy, Greece or Spain don't have the same situation as the others. We are on the only land migrant route which 700,000 people crossed in 2015. Today, thanks also to our efforts, the number of illegal crossings has been reduced to 2% of that figure. It's necessary to find a balance which will take account of the economy of every country. We must also find an arrangement with Turkey, we have no alternative."
Plenkovic explains why Croatia has not put up barbed wire to protect its border as Slovenia and Hungary have.
"That's not our policy. The border between Bosnia and Herzegovina and Croatia is 1,351 kilometres, longer than the border between Russia and Finland. In Bosnia and Herzegovina we have three constituent peoples: Croats, Bosniaks and Serbs. We don't want to erect barriers towards Bosnia and Herzegovina nor between Croatians."
Croatia has opted for a different model of border protection by strengthening the police, Plenkovic adds.
He believes the EU can and must recover from the UK's exit.
Speaking of the Conference on the Future of Europe, which is expected to result in proposals on how to best deal with challenges, Plenkovic does not rule out changes to the EU's basic treaties.
He expects the Zagreb Summit in May to be successful and the blockade of opening accession negotiations with North Macedonia and Albania to be lifted by then.
"It is our responsibility as a neighbour to Southeast European countries to say that it's necessary to send a positive message with the prospect of regular summits every two years. After Zagreb in 2000 and Thessaloniki in 2003, we had to wait 15 years for the Sofia Summit in 2018. I believe that, with a slightly improved accession process methodology, an agreement can be reached on opening negotiations with North Macedonia and Albania before the Zagreb Summit."