The U.S. State Department said on Saturday that Washington would not wait to impose sanctions on any shippers helping to get fuel to North Korea, in an apparent warning to Russia days after the U.S. ambassador to the United Nations accused Moscow of cheating on the measures.

North Korea continues to employ tactics to evade U.N. sanctions, Heather Nauert, the State Department spokeswoman, said in a statement, adding that U.N. member states are required to prohibit ship-to-ship transfers of petroleum fuel to the nuclear-armed country.

"The United States will not hesitate to impose sanctions on any individual, entity, or vessel supporting North Korea's illicit activities, regardless of nationality," Nauert said.