Photo via CGTN

Former US Secretary of State Colin Powell criticized President Donald Trump for threatening to use active-duty U.S. troops against protesters, saying it shows he has "drifted away" from the U.S. Constitution.

In a CNN interview, Powell aimed a broad critique at Trump's approach to the military, a foreign policy he said was causing "disdain" abroad and a president he portrayed as trying to amass excessive power. 

Powell, who served under Republican President George W. Bush, said he'll vote for Democrat Joe Biden in the general election.

"We have a constitution and we have to follow the constitution and the president has drifted away from it," Powell said on CNN's "State of the Union" on Sunday.