US President Barack Obama's national security advisor on Monday held bruising talks with top Russian officials in Moscow, days after the former foes exchanged Cold War-style blacklists in a row over human rights.
White House National Security Advisor Tom Donilon is the highest-ranking American to visit Russia since Obama's inauguration for a second term in January, but his trip coincides with one of the trickiest moments in bilateral relations in recent years.
Donilon held a morning meeting with Foreign Minister Sergei Lavrov who said that the American side had emphasised they did not want the "irritations" to spoil the strategic nature of US-Russia relations.
"We understand the importance of US-Russian cooperation for international relations. But removing the problems that have been growing in our ties remains for us priority number one," Lavrov told reporters at a later news conference with his Finnish counterpart.
The United States late Friday published a list of 18 Russians it was blacklisting over human rights abuses. Russia a day later angrily responded with a similar list of its own in a tit-for-tat move.
The US lists 16 Russians allegedly linked to the death of jailed lawyer Sergei Magntisky in 2009 as well as two Chechens who stand accused of murder. They are barred from travelling to the US or holding assets there.
Russia slammed the move as unfriendly and a day later hit back with its own blacklist of 18 Americans, including several well-known figures linked to detention practices at the Guantanamo Bay prison.
"The first person to feel the effects of Washington's blacklists is going to be T. Donilon. He is not coming to us at the best of times," the head of the Russian lower house of parliament's foreign affairs committee Alexei Pushkov wrote on Twitter.
Donilon is also to meet his Russian counterpart Nikolai Patrushev but in a sign of the chill in Russia-US ties, it is not clear whether he will meet President Vladimir Putin.
Putin's spokesman Dmitry Peskov said the Russian strongman might at some point "join in" the discussion between Patrushev and Donilon "if his working schedule allows".
The Kommersant daily said the Kremlin's refusal to confirm the meeting was a sign of its irritation with Washington, not just over the blacklists but over the fact Obama had failed to meet with Patrushev on one of his visits to Washington.
According to Lavrov, Donilon will be carrying a message for Putin from Obama over the prospects for bilateral relations.
Even before the blacklist row, the visit was seen as having huge importance as Obama looks for new bilateral nuclear weapons cuts and support from Russia in the North Korea crisis.
The US blacklist stems from the Magnitsky Act which Washington passed last year and infuriated Russia. Moscow responded by banning adoptions of Russian children by Americans, a move that caused an international outcry.
The death of Magnitsky in pre-trial detention in 2009 at the age of 37 -- after being accused of a fraud scam that he claimed to have uncovered -- has come to symbolise the Kremlin's failure to protect human rights.
Deputy Foreign Minister Sergei Ryabkov told the ITAR-TASS news agency at the weekend that the Russian blacklist also includes a secret section with more names, similar to a list of more highly placed Russian officials compiled by Washington.
According to The New York Times, the classified US list includes far more senior figures who include the controversial Chechnya leader Ramzan Kadyrov, and its publication would have caused an even greater row.
"Whether I am on the list - and I do not know if I am or not - makes no difference for me. I've never been to America and never plan to," Kadyrov said in a statement.