Washington has delivered high-level complaints to Moscow about accusations of increasing intimidation of American diplomats in Russia, the State Department said on Monday.
Secretary of State John Kerry last discussed the matter with Russian President Vladimir Putin on March 24, according to State Department spokeswoman Elizabeth Trudeau.
"We see an increase and we take it seriously," she told reporters at a press briefing.
Trudeau said that harassment of diplomats by Russian security agents and traffic police had been an issue over the past two years but did not detail any incidents nor why Kerry brought up the matter with Putin.
Other Western embassies had reported the same behavior toward their diplomats stationed in Moscow, Trudeau added.
Trudeau would not discuss specific incidents first reported by The Washington Post on Monday, including breaking into the homes of embassy personnel and moving around contents.
Moscow, however, has charged that Washington has also engaged in problematic behavior.
Last week the Russian Foreign Ministry Spokeswoman Maria Zakharova said that Moscow has "felt a significant increase in pressure on the Russian Embassy and consulates general of our country in the United States."
According to Zakharova, staff members of Russia's consulate missions abroad "regularly become the objects of provocations by the American secret services, face obstacles in making official contacts and other restrictions," including travel.
The Putin-Kerry conversation came after Washington in January stripped five of six Russian honorary consuls of credentials to retaliate for harassment of its diplomats in Moscow.
In response, Russia's Foreign Ministry accused the United States of provoking Russian diplomats in the United States and elsewhere.
Honorary consuls are typically U.S. citizens or green card holders who perform consular services outside Washington on behalf of a foreign government.
Trudeau couldn't rule out similar harassment by Russians of U.S. diplomats in other countries, but she said that she didn't have specifics of such cases occurring.