None of that matters to President Donald Trump, who announced Friday night that he would meet the globally shunned leader this Friday in Alaska. What does matter to Trump is that he may be able to stop the bloodshed in Ukraine, the worst European conflict since World War II, fulfilling one of his biggest campaign promises.

For President Vladimir V. Putin of Russia, it is an opportunity not just to end the Ukraine war on his terms, but to split apart the Western security alliance.

NATO Secretary General Mark Rutte said Friday’s summit between President Donald Trump and Russian President Vladimir Putin in Alaska will be an important test in ending the war in Ukraine.