Vejonis was joined by other heads of state from central and eastern Europe.
According to a statement from his office, Vejonis addressed the meeting and expressed gratitude for the presence of US troops and equipment on Latvian soil.
He also welcomed the opportunity to buy gas from the US, saying:
"The US initiative to send gas exports to Europe and Latvia is important, because our interest is in diversifying energy supply sources."
Later in the month he is due to meet with US Vice President Michael R Pence in Tallinn.