Ushakov met with reporters following Putin's closed-door meeting with visiting US National Security Advisor John Bolton at the Kremlin.
The Kremlin aide said the details of the forthcoming Putin-Trump summit were discussed and "a very convenient place has been chosen for us and for the US side."
Ushakov said the summit may last several hours with the two presidents first meeting tete-a-tete in the middle of the day and then together with delegations.
"They could agree on a joint statement outlining further steps from both sides to improve bilateral relations and joint actions in the international arena to ensure global stability and security," he said.
Ushakov said Putin discussed with Bolton priority issues that the presidents will address at the upcoming summit, in particular the Syria issue and its humanitarian aspect.
Putin reiterated that Moscow did not interfere in the 2016 US elections. Both sides discussed the Ukrainian settlement, but they did not mention the current US sanctions against Russia.
Earlier in the day, Bolton met with Russian Foreign Minister Sergei Lavrov and representatives of the Russian Security Council.