The antagonization of this fly by has been met with a barrage of condemnation from both the US, and Poland, who have commented that they can't treat the actions as anything other than an attempt at provocation. Poland is involved because of a presence of one of their military helicopters present on the USS Donald at the time of the fly by. The US and Poland have labeled the maneuvers as "simulated attack passes", while Russia claims that the passes were well within safety codes, and that they have no intentions of attacking either the US or any of the Baltic states, including Poland.
So what was the point of causing so much turmoil that could be easily done without? Much of the answer lies in the current rift between the US and Russia, as well as the current Russian political atmosphere. Putin is in an interesting position, one that requires him to carefully manage politics, economy, and reality and it is beginning to show which ones he has prioritized. As the Prime minister, he has reached deep into his bag of rhetoric to stance himself firmly across from NATO, blaming it and western states for much of the misfortune that has befallen the country after the international fallout of annexing Crimea.
Putin has taken many opportunities to flex this stance, especially in the Baltic sea, an area a little too close to home for the US to be sailing an Aegis equipped destroyer. The conflict in Syria has drawn the two opponents within friction range often lately, including the mobilization of Russian missile systems and the S-400 anti air network to the region. This incident is just another reminder of that proximity, and it is likely that Russia will answer in similar and increasingly aggressive fashion with each inch NATO creeps closer. But the real question is how much of this posture can Putin afford economically?
As the US steps up its modernization programs to bring its military another step into the future Russia attempts to keep pace, paying for it in economic hardship. With international sanctions and a plummeting energy market sucking the life out of the Russian economy, Putin has very little room to fund his adventures and hold together his endeavors to keep the stance against NATO strong. It is only a matter of time till Russia will have to start answering its national needs rather than try to prop up it's international conquests.