An elderly Ontario man who helped his daughter kidnap her two young sons and take them to Poland has been sentenced to 18 months of house arrest.

Ontario Court Justice Joseph Kenkel said on Tuesday that the sentence reflects the "essential" role Taduesz Ustaszewski played in planning and executing the abduction of 11-year-old Alexander Watkins and eight-year-old Christopher Watkins.

And if it wasn't for the 78-year-old's ailing health, Kenkel said he would have considered sending the grandfather to jail, in a case that has highlighted the legal challenges of bringing abducted Canadian children back from foreign countries.

"Whatever sentence is imposed in this case, it will be inadequate in the sense that I have no power to order the one thing that would matter most, the return of the children," the judge said in the ruling.

"Any sense of fairness or justice in the sentencing process is necessarily incomplete where the offence results in a victory for the offender and a terrible loss for the victim with no hope of remedy," he said.

"The impact on all of the victims of this offence has been serious and irreparable."

During the judge's remarks, Ustaszewski sat with a Polish interpreter and showed little reaction. He refused to speak with the media. 

The boys' father — Stephen Watkins, of Newmarket, Ont. — who was present for the hearing, was granted full custody of his children after he separated from his wife, Edyta Watkins, in August 2004.

The couple was engaged in a bitter, long-standing custody battle until March 2009 when she and the boys vanished, only to emerge later in Poland, her native country.

Last August, Ustaszewski was found guilty of being a party to child abduction — a rare conviction in Canada for someone who was not the main offender in the case.

The court found that Ustaszewski had picked up his grandchildren from school the day they went missing, and drove them and his daughter to the United States where the three boarded a flight to Frankfurt, Germany.

Kenkel said Ustaszewski had been "intimately involved" in his daughter's custody battle and had provided her a home to live in following the separation, gave her money and bought her and the grandchildren the airplane tickets with his credit card.

The judge pointed out that Stephen Watkins didn't know his children's whereabouts for 2 1/2 years, until he was contacted by authorities who reported they were now living in Poland, in a house paid for by Ustaszewski.

"As Mr. Watkins said, no parent ever thinks that when they drop their children off at school in the morning that they will never return home again," said Kenkel. "The abduction of Alexander and Christopher Watkins has been highly stressful and deeply painful."

Ustaszewski has been placed under strict conditions during his sentence, including not having any contact with his daughter or grandchildren, not be permitted to travel outside of Ontario and never leave his residence for the duration of his sentence.

He will also be subjected to two years of probation.

The Crown had originally asked for a one-year jail sentence, and the defence wanted only probation.

Outside the courthouse, Stephen Watkins called the sentence "bittersweet."

"It's not bringing my sons home," he said.   

Although there is an outstanding warrant for his ex-wife in Canada, his appeal to the Polish courts to have his children returned to him has been denied and the two countries do not have an extradition treaty in place.

Watkins — who has repeatedly urged the federal government to intervene in his case — said he still remembers what his oldest son, Alexander, said to him when they saw each other last during a court-ordered visit in Poland.

"When I was saying goodbye, he came over and he hugged me and said: 'I love you dad."'