The PSNI say Eastern European gangs are rearming republicans, using already established criminal networks to bring new weapons into Ireland.
Speaking to the Irish News Assistant Chief Constable Will Kerr has said that the recent gangland shootings in the Regency Hotel in Dublin during which David Byrne, a close associate of crime boss Christy Kinahan, was shot dead, showed the close links between various groups.
A man from Tyrone is alleged to have been involved in the attacks, with AK47s thought to have been from a republican weapons haul used in the shootings.
"It's not particularly difficult with the links into crime networks and Eastern European crime networks, worryingly it's not that difficult to get firearms," Mr Kerr said.
"And there are a number of what can be principally criminal routes that could be used to do that".
"The Dublin shootings were a good exemplar of the links between various groupings on the island of Ireland.
And the senior officer added: "To say that group is defined of those people and have this capability it's not that simple any more.
"There's this wide spectrum of groupings across the island of Ireland a lot of whom - most of whom - are involved in criminality for a variety of reasons either for an individual or for funding for an organisation.
"It is an increasingly difficult picture to define with any clarity," Mr Kerr said.
Recent bomb attacks by dissident republicans and weapons finds both north and south of the border have indicated a seizable sum of Semtex acquired by the Provisional IRA was held back from decommissioning.
"If you look at the simple fact that Semtex like that simply isn't made any more I think that answers the question in itself", said Will Kerr.
"Over the last number of years we've had a number of finds which involve Semtex and in some cases reasonably significant quantities of Semtex.
"So it's still not that difficult to get hold of worryingly," Mr Kerr added.
