Once the game starts, the moles will begin to pop up from their holes at random. The object of the game is to force the individual moles back into their holes by hitting them directly on the head with the mallet (source: Wikipedia).
The cartoon shows UK Prime Minister David Cameron shown playing Wac-a-Terrorist. The moles have been replaced by terrorists but the idea is the same: whenever you hit a terrorist in one country (Afghanistan, for example), another will pop up in a different country (most recently, Algeria).
1.The connotation of "Whac-a-mole" — or "Whack-a-mole" — in colloquial usage is that of a repetitious and futile task: each time an adversary is "whacked", or kicked off a service, he only pops up again somewhere else (source: Wikipedia).
2. The ease with which groups of al-Qaeda operatives were able to set up new terrorist operations prompted General David Petraeus, the former CIA director, to liken the agency’s counter-terrorism campaign to a “whack-a-mole” policy, saying that “you need to hit all the moles at once”.
If you whack someone or something, you hit them very hard. In the game Wac-a-Mole, the spelling is sometimes changed to 'wac' or 'whac'. In North American slang, to whack someone means to kill them deliberately.