"We have all the tools no-one can boast of... we will use them if necessary", he said, in what is seen as a reference to ballistic missiles and nuclear arms.
Ukraine's allies have stepped up the supply of weapons, with the US vowing to make sure Ukraine defeats Russia. Western officials say Russia is being hampered in its efforts in the east.
Last week, Russia launched a major offensive to seize the Donbas region after withdrawing from areas around the capital Kyiv. But according to one official, Russian forces are "finding it difficult to overcome the staunch Ukrainian resistance and they are suffering losses".
another development, the European Commission has accused Russia of
blackmail after Moscow cut off gas exports to Poland and Bulgaria. The Commission's President, Ursula von der Leyen said it showed Russia's "unreliability"... Read more and see video here.