KYIV — U.K. Prime Minister Keir Starmer has arrived in Ukraine to pledge more weapons and promise British support for the next 100 years, as the war against invading Russian forces enters a critical phase.

Almost three years since Vladimir Putin’s full-scale invasion began, Donald Trump is due to return to the White House as U.S. president and has pledged to end the war in short order.

At the same time, political forces sympathetic to Moscow are gaining ground across Europe — in countries including Austria, Romania and Germany.