The pair, aged 31 and 32, were detained in Lurgan, Co Armagh this morning under section 41 of the Terrorism Act.
Det Supt Karen Baxter of the TIU said a search was being carried out in Lurgan’s Victoria Gardens.
The men have been taken to the serious crime suite at Antrim police station for questioning.
They can be held for up to 48 hours for questioning before either being charged or released.
Detectives can also apply to a judge for an extension to their detention.