A youth has been arrested in Canada after an FBI tip-off on a charge of facilitating terrorist activity, authorities say.
The Kingston, Ontario resident faces an additional count of counselling a person to plant an explosive with intent to cause death or injury.
Police said a small plane recently spotted flying over the town at odd hours was part of their investigation.
A second individual was also arrested, but later released without charge.
The youth and the second person, an adult male, were detained on Thursday in Kingston, a city some 200km (125 miles) from Ottawa, the country’s capital.
Authorities described the pair as friends.
Under Canadian law, the identity of a youth accused of a crime is kept confidential.
Royal Canadian Mounted Police (RCMP) Ch Supt Michael LeSage said the force had received the tip-off from the FBI in December.
US authorities flagged to their Canadian counterparts a “substantiated and credible attack plot”, though there was no planned target or timeline, police said.
One home was evacuated in the early morning hours on Friday after police found what they believe was an “explosive substance” that was detonated by police bomb squads.
Ch Supt Lesage called the charges on Friday “significant”, but said there was no imminent threat to the community. The investigation is ongoing.
The second person was identified by the Canadian Broadcasting Corporation as a 20-year-old man from a Syrian family.
Kingston Archdeacon Bill Clarke confirmed to the BBC the family had come to Kingston as privately sponsored refugees in the summer of 2017.
A coalition of local churches came together three years ago to bring a refugee family to Canada.
Bronek Korczynski, one of the sponsors, told Reuters he was concerned the arrests could affect perceptions of Muslims and refugees in Canada.
“That is a fear, because that’s the kind of ill-informed knee-jerk reaction that puts any group in potential harm’s way,” he said.
The federal public safety minister said the country’s threat level remains at medium, where it has been since 2014.
Canada’s Public Safety Minister Ralph Goodale urged people on Friday not to jump to conclusions about the case before police had completed their work.