Russia on Tuesday warned that ties with the United States faced the threat of "new aggravations" as talks on embassy staffing numbers ended with no breakthrough.
U.S. officials led by State Department number three Victoria Nuland met in Moscow with Russia's Deputy Foreign Minister Sergei Ryabkov.
Consular services at the U.S. Embassy in Moscow have been severely hindered after Russia banned the mission from employing local staff as part of tit-for-tat sanctions.
Ryabkov said the talks had been "useful" but stressed that the officials had failed to make progress on the functioning of missions, including visas and rotation of personnel.
"There is very little progress when it comes to the substantive part of the problems that exist," news agency Interfax quoted Ryabkov as saying. "There is a risk of new aggravations."
"Americans are not heeding our logic or our demands," state news agency RIA Novosti quoted Ryabkov as saying.
In a statement later on Tuesday, the Russian Foreign Ministry said Moscow did not want to escalate tensions but warned Washington against further pursuing "confrontational" policies.
"We propose the removal of all restrictions that have been introduced on both sides over the past few years," the statement added.
'There must be flexibility'
In Washington, the State Department confirmed there was no breakthrough but said the two sides agreed to keep up lower-level talks.
"We expect parity on staffing numbers, and we expect visa reciprocity," State Department spokesman Ned Price told reporters.
"There must be fairness, there must be flexibility on the Russian side if we are to achieve an equitable agreement."
U.S. senators have urged President Joe Biden to threaten to expel Russian diplomats without progress.
The United States complains that Russia had included local staff, now dismissed, among the numbers of U.S. diplomats allowed in the country.
The two sides are embroiled in many disagreements, including over the conflict in Ukraine — which Ryabkov said was not discussed.
Joe Biden has increased pressure on the Kremlin since becoming U.S. president in January.
In May, Russia formally designated the United States an "unfriendly state."
Nuland arrived on Monday for a three-day visit that will include talks with President Vladimir Putin's foreign policy adviser Yury Ushakov, the Kremlin said.
Known for her tough line on Russia, she was allowed into Russia despite previously having been placed on a sanctions list.
In exchange, Washington issued a U.S. visa to a representative of the Russian Foreign Ministry.