Diplomatic efforts to end the largely deadlocked war in Ukraine have focused on Western guarantees of Ukraine’s future security. But the Kremlin says it must obtain its own “security guarantees” before laying down arms.

What President Vladimir V. Putin of Russia says is protection, however, would drastically limit Ukraine’s sovereignty, leaving it vulnerable to a renewed Russian attack and, many of its supporters believe, effectively turning it into a client state of Moscow. That tension over “security guarantees” — and the different ways in which the term is interpreted by the Kremlin and by the West — underlines the fundamental challenge of forging any peace deal to end Russia’s invasion.

What Mr. Putin says are Russia’s rightful national security demands have been consistent for years. They reflect a list of grievances that he refers to in shorthand as “the root causes” of the war.

Under President Trump, Russia’s concerns are finally “being heard” in Washington, Mr. Putin says. “We can see now that some mutual understanding is taking shape,” Mr. Putin said at a summit in China this week, referring to his meeting with Mr. Trump in Alaska last month.

But many supporters of Ukraine believe that Mr. Putin’s frequently voiced concerns about NATO reflect his desire to subsume Ukraine and resurrect the Soviet Union.

Here’s what Russian officials mean when they talk about security guarantees and how that compares with the Ukrainian position.