A fresh round of alarm?
I found this phrase in the sentence,
"The disruption at Deutsche Telekom, which began on Nov. 27, set off a fresh round of alarm over potential Russian meddling and the vulnerability of Germanys computer networks, which could be disrupted or hacked during an election."
in an article of New York Times.
What does "fresh round" mean? How does it sound different from saying "set an alarm" instead? Also "set off" means simply "set"? I checked a dictionary but it only showed "start a trip".
Thanks in advance!