Amid a broadening investigation of Russian contacts with his associates and his own role in trying to stop it, President Trump fired off another angry tweet this past week repeating his assertion that he has no business interests in Russia.

But while no Trump Tower graces the Moscow skyline, the Russian authorities recently made sure that another piece of valuable property — the intellectual kind — bearing the same name remained safely in Mr. Trump’s portfolio.

Last year, while hacking Democrats’ emails and working to undermine the American presidential election, the Russian government also granted extensions to six trademarks for Mr. Trump that had been set to expire. The Trump trademarks, originally obtained between 1996 and 2007 for hotels and branding deals that never materialized, each had terms that were coming to an end in 2016.

Despite their inactivity, the Trump Organization sought extensions for the trademarks from Rospatent, the Russian government agency in charge of intellectual property. In a series of approvals starting in April 2016 and ending in December, Rospatent granted new 10-year terms for the trademarks, the agency’s records show.