"This is not just a scandal - it's a crime with serious legal consequences," Ukraine's ambassador to Germany, Andriy Melnyk, told a group of newspapers after techno band Scooter crossed from Russia into Crimea to play the ZBFest music near Sevastopol this weekend.

Ukrainian law prohibits people from travelling to Crimea, which was de facto annexed by Russia in 2014, via any border crossing not manned by Ukrainians. The German Foreign Ministry strongly warns against going to Crimea, as do many other countries' foreign ministries. The EU currently maintains a battery of sanctions against Crimea.

"This is not a misdemeanor - it's a serious crime that gets prosecuted around the world," Melnyk said, adding that criminal investigations had been initiated. A Ukrainian news agency reports that Ukraine is currently seeking legal assistance from Germany and that Scooter's members could be sentenced up to eight years in jail.

At the very least Scooter faces a ban from playing in Ukraine. This May, the Russia entrant in the Eurovision Song Contest, Yulia Samoilova, was refused entry to Ukraine on the grounds that she had illegally travelled to Crimea.

Melnyk also suggested that Scooter's frontman should be fired from his role in Germany's most popular TV music casting show. Melnyk said the show's producers should ask themselves "whether H.P. Baxxter - someone who knowingly violated the laws of a country and endorsed the illegal annexation of Crimea - is fit to be a juror for 'Germany's Next Superstar.'"

A purely musical event?

The concert underscores the dilemma of how Western Europeans should treat Crimea.

"We see this as a purely musical event and are playing for our fans," Baxxter told the dpa news agency on the eve of the concert. "We're not going to let ourselves be coopted politically."

After the gig, Scooter posted a photo of the concert on their Facebook page with the message "Thank you Crimea, amazing crowd!" but didn't mention the controversy. Reactions of users were mixed.

"I don't understand people getting mad at them," wrote one person in English. "So the Crimean civilians should be deprived of music just because stupid Russia illegally annexed them? What sense does that make?"

Others condemned the concert.

"You should be ashamed, Scooter!" wrote one user in German. "I'm no longer a fan! What ignorance!"

Politics parallel pop

This is the same dilemma German politicians are currently facing. The official policy of the EU is that the Russian annexation of Crimea is illegal. The German government resists any debate about the status of the peninsula and says that there is no reason to discuss the loosening of sanctions right now.

But it does want to decouple the issue from that of armed conflicts between Russian separatists and Ukraine in eastern Ukraine.

"It is part of the European consensus that we should first concentrate on a political solution to the bloody conflict in eastern Ukraine, which claims new victims every week, and then put Crimea on the agenda in a later political process," the government's commissioner on Russia, Gernot Erler, told a group of newspapers.

A lasting provisional state of affairs

The head of the Free Democratic Party (FDP), Christian Lindner, wants to go further in acknowledging what he says is the reality in Crimea.

"Europe's security and prosperity also depend on relations with Russia," Lindner told a group of newspapers. "To broach a taboo subject: I'm afraid that we will have to treat Crimea, for the time being, as a lasting provisional state of affairs."

He added that the West should consider loosening sanctions as an incentive for progress made in other areas of the Russian-Ukrainian conflict and that the issue of Crimea should be "isolated." Lindner's words carry weight because as FDP leader, the party traditionally favored as a coalition partner by Angela Merkel's conservatives, he could well become Germany's next foreign minister.

The Greens accused Lindner of deviating from his own party's policy, which demands that Russia end its "occupation" of Crimea. Green Party co-leader Cem Özdemir said Lindner apparently wanted to form "a new coalition of friends of dictators," together with the Left Party. The Left, the successor to the socialist party in communist East Germany, is the only major party in Germany not to officially condemn Russia's annexation of Ukraine.

Ambassador Melnyk responded to Lindner's comments in a tweet, writing: "My dear Mr. Lindner, I'd be grateful, if we could meet soon to talk about Crimea. It's very important!"