In Spanish in Latin America or in Arabic across the Middle East, a steady stream of Russian propaganda and disinformation continues to try to justify President Vladimir V. Putin’s unprovoked invasion, demonizing Ukraine and obfuscating responsibility for Russian atrocities that have killed thousands of civilians.

The result has been a geographical and cultural asymmetry in the information war over Ukraine that has helped undercut American- and European-led efforts to put broad international pressure on Mr. Putin to call off his war.

“There is not an airtight, worldwide stifling of Russia’s notorious ability to fight not only on the battlefield, the real battlefield, but also to fight with information and distortions of information,” said Paul M. Barrett, deputy director of the Stern Center for Business and Human Rights at New York University, who recently wrote a study about the spread of harmful Russian propaganda on YouTube.