Chroniton torpedo

Chroniton torpedoes were weapons capable of penetrating an opponent's shields because the shields were in a state of temporal flux. These weapons were used by the Krenim Imperium and the Tandaran Empire of an alternate universe.

In 2373, a Tandaran warship used a track-jumper to enter the primary universe and then assaulted the Department of Temporal Investigations branch office on Aldebaran III with chroniton torpedoes. 

In 2374 of an alternate timeline, a fragment from a Krenim torpedo lodged itself in the haul of the USS Voyager, leaking chroniton radiation into the ship. This radiation later caused Kes to jump through time, a process [[the Doctor was eventually able to stop.

In the same alternate timeline, Voyager's crew managed to counter the effects of the torpedo, but this timeline was erased anyway when a Krenim warship was destroyed.