NATO will not allow Moscow to blackmail the alliance and will not accept a Russian veto against an enlargement, German Defense Minister Christine Lambrecht said on Friday.
"Russia does not have a veto in issues concerning the alliance and cannot blackmail us. These red lines must be clear in all pending talks," she told parliament, Reuters reported.
"But between these red lines and a military conflict, there is a lot of scope that we must make use of", Lambrecht said, adding she would meet NATO Secretary-General Jens Stoltenberg in Berlin next week.
In another development, Ukrainian military intelligence said on Friday that Russian special services were preparing what it called "provocations" against Russian servicemen located in Moldova's breakaway region of Transdniestria in order to accuse Ukraine.
It said in a statement that the provocations may be against Russian armed forces' artillery depots.
Ukraine was hit on Friday by a massive cyberattack warning its citizens to "be afraid and expect the worst." Russia, which has massed more than 100,000 troops on its neighbor's frontier, meanwhile released TV pictures of more forces deploying in a drill.