The Federal Bureau of Investigation acted properly when it began a broad investigation into whether then-candidate Donald Trump or people around him conspired with Russia to interfere in the 2016 election, according to the Justice Department's inspector general.

"The FBI had an authorized purpose when it opened" the probe "to obtain information about, or to protect against, a national security threat or federal crime, even though the investigation also had the potential to impact constitutionally protected activity," according to the 434-page report released Monday by Inspector General Michael Horowitz.

The report assesses some of the earliest actions that FBI and Justice Department officials took during their investigation into Trump and his campaign starting in 2016. The president and his conservative allies have long alleged that he was targeted for politically motivated spying in an effort to undermine his candidacy and presidency.