Police said they believe the recovery of a rocket launcher "has saved lives".
The Police Service for Northern Ireland has has been on high alert after a series of attempts by republican dissidents to kill members of the security forces.
These weapon systems are clearly intended to kill and we should be in no doubt that the recovery of these items has saved lives.
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Explosives experts were called to the nuclear reprocessing site in Cumbria, to help deal with chemical substances.
The arrests were made on suspicion of producing and disseminating pedophilia content on the internet, the country's Justice Ministry said.
The A4-sized sketch originally went for £75 when it was first sold.