It’s the same type freak out that happened when Gorbachev was negotiating (actually being swindled, which was a VERY good thing) the end of the Warsaw Pact. The commie stooges like Jaruzelski and Honecker were completely against their countries being freed from under the Soviet boot heel because it meant the end of their power. Our European vassal state leaders are terrified that Trump is about to disengage the American big brother from the continent. They don’t want to have to stand on their own and deal with the Russians or the Germans or the Turks, etc. Let the American sugar daddy continue to force them to make nice with each other and to protect them from any other nation that they might blunder into a conflict with.
I don’t know that swindling Gorbachev was such a great maneuver. If the Soviet Union had more slowly evolved into a democratic welfare state like France, Germany, or Sweden rather than jolted into a quasi-anarcho-capitalist mess that resulted in theft and corruption by oligarchs then Europe as a whole might have been in a much better position.