President Barack Obama's top security aide on Monday handed President Vladimir Putin a "constructive" message from the US leader, the Kremlin said amid new tensions in relations.
National Security Advisor Tom Donilon personally handed Putin the message after the Russian president joined Donilon's talks with his Russian counterpart Nikolai Patrushev, the Kremlin said in a statement.
The Kremlin had confirmed Putin's participation in the talks only at the last moment.
The statement gave no further details on the contents of the message, but Putin's foreign policy advisor Yuri Ushakov said it contained proposals on nuclear weapons arsenals, missile defence and improving bilateral trade.
Ushakov did not specify further but expressed satisfaction with the message, which he said contained some new ideas.
"The message is written in a very constructive tone and contains a range of suggestions for further deepening of our bilateral dialogue and cooperation," he said, quoted by the Interfax news agency.
"Some ideas have already been talked about but there are some new elements which our country will study in the most attentive way and give a corresponding response," he added.
The visit by Donilon -- the highest-ranking American to visit Moscow since Obama's inauguration for a second term in January -- is taking place under the shadow of a new diplomatic row between the former foes.
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.