Speaking for Serbia's state broadcaster RTS in Moscow late on Thursday, the prime minister said: "We must have a serious and responsible response and it will come in the days ahead of us, and it concerns above all the European Union and their attitude toward us all. We'll see, I shouldn't prejudice."
Asked to comment on "why Brussels is silent on the issue for now," Vucic said that "speaks very strongly in itself."
He described Pristina's decision as "difficult and bad news, and at the very least, irresponsible behavior."
"Somebody would say that one can always expect this from Pristina, and I think it is unexpected news because this is very irresponsible behavior. That's the mildest term I can use, without giving any further assessment," said he.
Vucic stated that the Brussels agreement was negotiated for months, that the talks were "difficult and full of compromise," and that "signatures that are now not respected were put on it."
"Somebody put their signature, my signature means something, the signature of anyone from Serbia meant something for me, of Borko Stefanovic, Boris Tadic, and Ivica Dacic. To them (Pristina) their signatures mean nothing, and they did that a day after they got the Stabilization and Association Agreement with the EU," Vucic said.
"Agreement has to be respected"Both parties in dialogue on normalization of Belgrade-Pristina relations have to implement what has been agreed, Maja Kocijancic, the spokesperson of EU High Representative for Foreign Affairs and Security Policy Federica Mogherini, said late on Thursday.
"Everything that has been agreed in the context of dialogue should be implemented regardless of internal procedures that we do not want comment," Kocijancic said when asked how Brussels will react to Pristina's decision to postpone the implementation of the agreement on the ZSO.
Pristina has postponed the agreement until the local constitutional court evaluates the constitutionality of the agreement reached in Brussels in August.