Tankers!
This operation will net you a very helpful 1000 bonus XP! You know the drill, earn the achievement to grab the reward as many times as you can during the dates and times below!
The operation starts 03:30 PST December 24, 2012 (11:30 UTC) and runs through 03:00 PST December 28, 2012 (11:00 UTC).
Top Gun
Destroy more enemy vehicles than any other player on your team (at least 6). If two or more players have destroyed equal amount of vehicles, the achievement is granted to the player who has earned more XP for the battle, including additional XP provided to Premium account users.
That's a pretty sizeable chunk of XP, and the best part of Operation: Top Gun is that it's repeatable; you'll get this reward every time you meet the above criteria as long as the event is active.
Good luck!