Ukrainian leader Volodymyr Zelensky on Tuesday demanded an immediate halt to the Nord Steam 2 project and Kyiv prepared to sever relations with Moscow in response to its recognition of two breakaway regions.
Zelensky also told reporters that the Kremlin was paving the way for a major military assault on Ukraine.
The Ukrainian leader said Russian President Vladimir Putin's actions on Monday demanded a swift and punishing economic response from the West.
He said it must include "the complete stop of the Nord Stream 2" project that takes Russian gas to Germany under the Baltic Sea.
The pipeline -- completed but not yet in operation -- has also angered Washington and Ukraine's close allies in eastern Europe.
German Chancellor Olaf Scholz appears to have warmed to the idea of suspending the project after initially refusing to give unequivocal support to such a move.
Zelensky said he has also "received a request from the foreign ministry to examine the question of breaking off relations between Ukraine and the Russian Federation".
"I will now, immediately after this press conference, examine and work on this issue," he said at a joint media appearance with Estonian President Alar Karis.
He called Putin's recognition of the rebel Donetsk and Lugansk regions the first step to a planned "military aggression against Ukraine".