During a visit to Serbia, European Union enlargement commissioner Johannes Hahn has urged the country to implement “difficult reforms” and to normalize ties with Kosovo in order to be able to join the bloc by 2025.

Hahn began a tour to Serbia and Montenegro with a stop in Belgrade on February 7, the day after the European Commission unveiled its new strategy to integrate the six Western Balkan countries that remain outside the EU.

The strategy is meant to give a clear view toward EU accession to Albania, Bosnia-Herzegovina, Kosovo, Macedonia, Montenegro, and Serbia.

Among the six countries, the commission considers Serbia and Montenegro as current front-runners toward accession and the new strategy says they could be allowed in by 2025 if they meet all the conditions.

Speaking at a joint news conference with Serbian President Aleksandar Vucic, Hahn said that the country’s “EU perspective is real and the country now has a unique opportunity to grasp it.”

“Reforms will be tough and the EU accession process is not an easy ride,” he said, adding that the European Commission will “always be here to support you.”

Vucic acknowledged that there was a “mountain chain of obstacles” on Serbia’s EU path and said it would be up to the Serbian citizens to choose the country’s path.

“[The government and the president] will come up with suggestions, but the decision is not on us. The decision is on the citizens. We won’t be able to [act] against the people’s will. Citizens will have to say how they see the future of our beautiful country,” he said.

Hahn said that a “strong political push” will be needed to deliver on “sometimes difficult reforms, in particular, on rule of law, justice, and fundamental rights.”

“We need to see fundamental changes in these areas across the Western Balkans,” the commissioner insisted.

He said Serbia also needs to “conclude and irreversibly implement a legally binding agreement with Kosovo before it can join” the EU, and thanked Vucic for “the internal dialogue he has launched on this vital issue.”

“The EU cannot and will not import bilateral disputes,” Hahn said.