NATO has been informed of the Ukrainian Verkhovna Rada's decision to codify Kyiv's course toward entry into the alliance.
Ambassadors of the European Union’s 28 member states have approved the decision to extend sanctions against Crimea for another year.
Thousands of troops from NATO and its partner nations are training on land and sea in central and eastern Europe.
Though he denied the Russian state had been involved in hacking, Putin said individual "patriotic" hackers could mount their own attacks.
Russian state gas exporter Gazprom, which supplies around a third of the EU's gas, is keen for Nord Stream 2 to be built by 2019.