front and center of everything the US does is the domestic political angle.
as things stand, democrats will lose congress (badly) in november.
historically, starting a war has offered a number of angles to change an unattractive domestic political situation.
the folks running the show could not care less how many americans they get killed as long as they solidify their grasp on power. this isn’t a unique situation, historically. russia/china know it too, and have more or less said so openly.
There are a lot of possible reasons for what Lithuania has done, including this.
We can speculate, but no one on this forum has the inside information required to actually know for sure.
About all we can say for sure is that what Lithuania did is a definite escalation, and a response by Russia is probable.
That said, my personal opinion is that you are right. It may not be the ONLY reason, but in my opinion the people pulling Biden's strings expect a response by Russia, and plan to use that response to further their own political objectives.
They are playing with fire. They do not care.