"We've shot ourselves in the foot so much we don't know today what situation we're in," he said in an interview published by the public broadcaster LRT on Wednesday.
Nauseda described the discussions on the German brigade as premature, noting that, first of all, the country has to be ready to host allied troops.
"Today, for one reason or another, we are starting to question not only our own readiness, but also that of our ally who (...) demonstrated the initiative to take more responsibility for our security," the president said.
"Today we are trying, or some politicians are trying, to send signals of distrust, which is completely incomprehensible to me," he added.
Nauseda noted that the communiqué on the brigade had been issued before NATO's Madrid summit where the Alliance's leaders agreed to beef up its eastern flank and that Germany had been sending signals before the meeting that it was ready to increase its military presence in Lithuania.
"My suggestion is that we look at what we have achieved and answer the question if Lithuania feels safer today than it did, for example, in May," the president said.
"I can say that Lithuania feels safer. The German forward command element is already here, the plans for organizing further exercises and deploying troops are already in place, and it depends on us how things will go further," he added.
Nauseda called on politicians to stop "making noise about nothing" and instead focus on implementing plans for making Lithuania ready to host allied troops.
The joint communiqué signed by the Lithuanian president and German Chancellor Olaf Schulz in June says that "in addition to the current and reinforced enhanced Forward Presence Battle Group already in place, Germany is ready to lead a robust and combat-ready brigade in Lithuania dedicated to deter and defend against Russian aggression".
Germany has so far only deployed the brigade's forward command element to Lithuania.
Vilnius wants a full rotational German brigade to be permanently deployed in the country. Berlin officials, however, have said on numerous occasions that part of the brigade will be deployed in Lithuania and the rest will stay at home but will be ready to redeploy quickly if necessary.
This has sparked discussions in Lithuania about Germany's commitment to deploy a brigade-sized unit in the country.