British Prime Minister Boris Johnson lauded Ukraine for its "indomitable" resistance to Russia's invasion during a surprise visit to Kyiv on Wednesday, and said now was not the time to promote a "flimsy plan for negotiation" with Moscow.
Johnson, who is due to leave office next month, spoke at a joint news conference with Ukrainian President Volodymyr Zelenskiy on his fourth trip to Ukraine this year as Ukraine celebrated 31 years of independence from the Soviet Union.
Johnson, whom Zelenskiy described as his "dear friend Boris", said it was vital that Europe keep up its military and economic support for Ukraine even as rising energy and food prices were causing some consumers pain.
"We also know that if we're paying in our energy bills for the evils of Vladimir Putin, the people of Ukraine are paying in their blood," Johnson said.
"And that's why we know we must stay the course. Because if Putin were to succeed, then no country on Russia's perimeter would be safe, and ... (that) would be a green light for every autocrat in the world that borders could be changed by force."
Johnson's trip coincided with the six-month anniversary of what Moscow calls its special military operation. It came amid fears that Russia could again launch missiles at major cities in Ukraine to cast a pall over Ukrainian Independence Day.
Air raid sirens sounded several times in Kyiv on Wednesday.
"To all our friends, I simply say this, we must keep going. We must show as friends of Ukraine that we have the same strategic endurance as the people of Ukraine," Johnson said.
Johnson has been among Ukraine's most vocal backers during the war.
Zelenskiy said it was vital Ukraine and the West did not allow Moscow to seize the momentum in the war.
"We cannot relax, we cannot freeze the conflict, we cannot wait a year, or two, or three... We cannot, under any circumstances, give up the initiative," Zelenskiy said.
The Ukrainian leader thanked Johnson for "the uncompromising support for our country from the first days of the full-scale Russian aggression."
(Reporting by Tom Balmforth, writing by Andrea Shalal; Editing by Toby Chopra and Jonathan Oatis)