Vladimir Putin Sowed Seeds of His Downfall by Invading Ukraine—U.K.

Russian President Vladimir Putin "sowed the seeds of catastrophe" for himself by invading Ukraine, British Prime Minister Boris Johnson told Ukrainian lawmakers on Tuesday.

Addressing Ukraine's parliament Verkhovna Rada in Kyiv by video link, Johnson said that "Putin's mistake was to invade Ukraine, and the carcasses of Russian armor littering your fields and streets are monuments not only to his folly but to the dangers of autocracy itself. What he has done is an advertisement for democracy."

Britain has been one of Ukraine's closest allies during the war, supplying the eastern European country with huge tranches of weapons and millions of pounds worth of military aid.

"When a leader rules by fear, rigs elections, jails critics, gags the media, and listens just to sycophants—when there is no limit on his power—that is when he makes catastrophic mistakes," Johnson added.

In his Tuesday address to President Volodymyr Zelensky and Ukraine's parliament, Johnson criticized the west for being too slow to act against Russian aggression against its neighbor. He said the west made a mistake to not help Ukraine in 2014 after Russia annexed the Crimean Peninsula.

"We, who are your friends, must be humble about what happened in 2014 because Ukraine was invaded before for the first time when Crimea was taken from Ukraine and the war in the Donbas began," Johnson said. "The truth is that we were too slow to grasp what was really happening and we collectively failed to impose the sanctions then that we should have put on Vladimir Putin," he added.

"We cannot make the same mistake again."

Johnson praised the tenacity of the Ukrainian people in fighting the Russians.

"Your children and grandchildren will say that Ukrainians taught the world that the brute force of an aggressor counts for nothing against the moral force of a people determined to be free," he said, before noting the "terrible price" the Ukrainians had paid.

Johnson also announced details of 300 million pounds ($375 million) in extra military aid for Ukraine, which includes electronic warfare equipment, a counter-battery radar system, GPS jammers and thousands of night vision devices.

The U.K. has provided Ukraine with javelins—portable anti-tank missile launchers—as well as lightweight air defense systems.

Britain is also supplying Ukraine with heavy-lift aerial drones to help carry supplies to isolated Ukrainian forces, as well as 13 specialized Toyota Land Cruisers to help evacuate civilians and help officials rebuild infrastructure in eastern Ukraine.

Johnson vowed that the U.K. would continue to supply Ukraine with military equipment.

Newsweek reached out to the Kremlin for comment.