"The key topics will be security and (...) the upcoming NATO summit," he said.
According to the diplomat, issues of major importance to Lithuania include the presence of NATO battalions and the United States in the region and the strengthening of its air defence.
Economic relations, including US liquefied natural gas imports to Lithuania, are also among issues planned to be discussed during the meeting, he said.
Aleksiejūnas noted that the US has given a high diplomatic status to the visit, which is called in the diplomatic language a US-Baltic summit, rather than a working visit.
Eastern European countries were worried by Trump' presidential election campaign promise to improve relations with Russia and his statements that NATO was "obsolete". Lithuanian officials are watching with concern the US president's rows with America's allies in Europe and his often unpredictable behaviour.
An opinion poll showed earlier this month that two-thirds of Lithuanians did not trust Trump to make the right decisions on key political issues.
However, diplomats and Trump's supporters underline that he softened his rhetoric about NATO after becoming US president and that officials in his administration pay great attention to the Baltic countries.
After Russia annexed Ukraine's region of Crimea in 2014, the US immediately sent several hundreds of troops to each Baltic country. The American companies were withdrawn following the deployment of NATO's multinational battalions in Lithuania, Latvia and Estonia and US troops now come for training from neighbouring Poland.