The Trump administration announced a series of sanctions on Tuesday targeting Russia, including ships that are delivering Russian oil to North Korea despite ongoing sanctions and marine companies that are supplying Russia’s military.

The ships, based in Vladivostok and operating for Primorye Maritime Logistics Co. and Gudzon Shipping Co., have defied international sanctions against North Korea by engaging in ship-to-ship transfers of oil to North Korean ships, which then bring the contraband into North Korean ports.

The Trump administration has been warning against this practice for months. But while negotiations with North Korea were going well, the administration largely turned a blind eye to the problem.

The marine companies were sanctioned for doing business with a Russian company, Divetechnoservices, that the Trump administration had sanctioned on June 11 over its links to Russia’s Federal Security Service, or F.S.B., the main security and intelligence agency in the country.