By James Helm
BBC Dublin correspondent
In the depths of summer, when most of Ireland's leading politicians would be hoping to relax and enjoy their holidays, its government has a major political headache.
The men were initially acquitted of training Farc insurgents
The men who are becoming known as the "Colombia 3" - James Monaghan, Niall Connolly and Martin McCauley - are back in Ireland.
They disappeared while on bail after being sentenced to 17 years in prison in Colombia last year.
Their supporters were delighted to welcome them back after a long campaign to bring them home.
Ireland's government, though, is less than pleased.
The appearance of one of the men, Mr Monaghan, out of the blue on Irish television last Friday has brought acute diplomatic embarrassment.
Irish Prime Minister Bertie Ahern, had to interrupt his holiday in the west of Ireland. Now his government is talking of what to do next.
Mr Monaghan, Mr Connolly and Mr McCauley are all Irish republicans.
They were arrested at Bogota Airport in August 2001 as they were about to leave Colombia, and they were travelling on false passports.
They had been in areas of the country controlled by the Farc rebels. The men maintained they were there for bird watching, and to lend their support to the Colombian peace process.
But they were accused by the Colombian authorities of aiding the rebels and teaching them bomb-making techniques.
They were initially acquitted, but last December a government appeal led to the men's conviction and 17-year jail sentences.
Released on bail, they then disappeared.
Then, last Friday, came their startling re-appearance on Irish soil.
Mr Monaghan insisted he was not on the run, but would not say how the trio travelled back to Ireland - a source of much speculation in the country.
The Irish police are searching for the men. The Colombian government wants them back immediately, stressing Ireland's "legal and moral obligation" to return them.
Unionist politicians in Northern Ireland are furious, but Sinn Fein has welcomed their safe return.
Some in Ireland have wondered whether the men's return was part of some political deal - an idea the Irish government has firmly rejected. It has hurriedly briefed officials from the British and American embassies in Dublin.
Now, Mr Ahern's deputy, Mary Harney, has entered the fray. She called on the three men to walk into their nearest police station and give themselves up.
She has also suggested that new legislation might enable the men to serve out the remainder of their prison sentences on Irish soil.
"These three individuals were no ordinary tourists visiting Colombia, and justice must be seen to be done," she said.
Farc has waged a 40-year insurgency in Colombia
Of their return, Ms Harney added: "I'm extraordinarily concerned about how they got back into the country. The fight against international terrorism is something we all have a huge role to play in."
She called on the Sinn Fein leader, Gerry Adams, to help the police in their search for the men.
On the legal front, Ireland has no extradition treaty with Colombia and no formal request for the men's extradition has yet been received.
Supporters of the men point to Colombia's human rights record as a reason for them not to be sent back.
They have complained throughout that the men were not treated fairly. Mr Adams, for his part, has said the men should now be left alone with their families.
For all its talk and angry words, it is not clear if the Irish government can actually do much just yet.
The precise whereabouts of the men in Ireland is unknown
As Ms Harney pointed out, extradition is a legal matter and the legal wheels may now take some time to turn.
First, of course, the men have to be found.
For some Irish politicians, the appearance of Mr Monaghan on their TV screens meant their hopes of a quiet summer disappeared - and a legal and political problem arrived.