$a="11.12.1984"
write-host "date a: $a"
$provider = New-Object System.Globalization.CultureInfo "ru-RU"
$c=[datetime]::ParseExact($a,"dd.mm.yyyy",$provider)
write-host "date c: $c"
date a: 11.12.1984
date c: 01/11/1984 00:12:00
###########
$a="11.12.1984"
write-host "date a: $a"
$provider = New-Object System.Globalization.CultureInfo "ru-RU"
$c=[datetime]::ParseExact($a,"mm.dd.yyyy",$provider)
write-host "date c: $c"
date a: 11.12.1984
date c: 01/12/1984 00:11:00