A 25-year-old Beechboro man has been charged as part of an investigation into child exploitation.
"The investigation was the result of information received from the American-based National Centre for Missing and Exploited Children after it is alleged the man engaged online with three female children in the USA," a WA Police spokeswoman said.
Two of the girls were aged 13 and one was 15.
"It is further alleged that during these online conversations the man exposed the three children to indecent material," the spokeswoman said.
The National Centre for Missing and Exploited Children provided the details to WA Police via the Australian Federal Police.
"It will also be alleged that in September 2013, the man used online social chat facilities to engage in conversation of a sexual nature with a person he believed was a 14-year-old girl," the spokeswoman said.
The "girl" was a West Australian police officer from the Online Child Exploitation Squad.
Police allege the man exposed the "girl" to indecent matter and was arrested at his Beechboro house on Monday.
"During a search of the premises, police seized various electronic equipment including computers, mobile phones and a small amount of cannabis and drug paraphernalia," the police spokeswoman said.
Online Child Exploitation Squad Detectives have charged the man with four counts of intent to expose a person believed to be under-16 years to indecent matter and one count each of possessing drug paraphernalia in or on which there was a drug or plant and possessing a prohibited drug.
The man is expected to appear in Midland Magistrate's Court on January 6.