Russia's foreign minister says the removal of the Russian flag from the seized diplomatic facilities is unacceptable.
Russian Foreign Minister Sergei Lavrov told US Secretary of State Rex Tillerson on Thursday that Russia was preparing lawsuits to reclaim what Moscow says was illegally seized property in the United States.
Lavrov, in a telephone conversation with Tillerson, also said it was unacceptable that US authorities had removed Russian flags from its seized diplomatic buildings in the United States, the ministry said.
US State Department spokeswoman Heather Nauert, asked about the accusations later, told reporters that US actions at the shuttered Russian facilities were "perfectly legal" and were carried out with "a lot of thought" and in a "judicious fashion."
"The flags of the former Russian consular properties in San Francisco were respectfully lowered. They're safely stored within each of the buildings," Nauert said. "There's no country in the world that pays greater respect to its own flag and to the flags of other nations. That is something that we take seriously."
But Russia's foreign ministry said Lavrov stressed to Tillerson that "the lawlessness continued by US officials runs counter to declarations made at the highest level in Washington about intentions to normalise the bilateral relations, which have hit an all-time low."
Russian staff left the consulate in San Francisco last month after Washington ordered Moscow to vacate some of its diplomatic properties, part of a series of tit-for-tat actions resulting from a souring of relations between the two countries.