The men aged 33, 32, 30 and 29 have been charged with a number of offences related to drug trafficking and money laundering.
Officers recovered £800,000 of ‘skunk’ and cash during searches in Belfast, Greenisland, Bangor, Newtownards and Ballywalter.
Six people were arrested.
A further eight were arrested n Italy by its Caribinieri.
The men who have been charged are due to appear at Newtownards Magistrates’ Court on Thursday.
On Wednesday evening a 37-year-old man was arrested in England, to be brought to Northern Ireland for questioning.
He was detained by police in Birmingham but was transferred to Northern Ireland to be interviewed by detectives from the PSNI’s Organised Crime Branch.
The six people arrested in Northern Ireland were four men and two women who were questioned on suspicion of the importation of cannabis and conspiracy to supply cannabis and money laundering.
The two women, aged 29 and 26, have since been released on police bail pending further inquiries.