SEVASTOPOL, Crimea — With a single diesel-electric submarine and a hodgepodge of other aging vessels, Russia’s rickety Black Sea Fleet would be no match for the United States’ Sixth Fleet, based in Italy, which boasts the latest in seaborne military technology and has been running drills nearby.

Still, the legendary Russian fleet, whose headquarters have been here since 1783, is within a day’s sailing of the Mediterranean and remains crucial to the Kremlin’s ability to exert strategic influence in the Middle East and beyond.

Safeguarding this maritime muscle may well have been one reason President Vladimir V. Putin of Russia sent armed forces to seize Crimea. But is it possible that the Sevastopol base is just the most concrete manifestation of Russia’s deep interests in Ukraine that the United States and its NATO allies either ignored or forgot as they tried to bind it more tightly with the West?

For years, Mr. Putin has complained about the West moving unilaterally to reorder the Continental balance of power — promoting Western capitalism and democracy — with little indication anyone was heeding his concerns. Its courting of Ukraine, apparently, was a step too far, prompting Mr. Putin to risk sanctions and the worst conflict since the Cold War to make clear that Washington and its friends do not call all of the shots anymore.