However it is also commonly said that a "fourth estate" (or branch) exists, and the top search result that I get for that phrase is:
"What is the role of the Fourth Estate?
In the United States, the term fourth estate is sometimes used to place the press alongside the three branches of government: legislative, executive and judicial. The fourth estate refers to the watchdog role of the press, one that is important to a functioning democracy.Jan 3, 2019
What is the Fourth Estate? - ThoughtCo https://www.thoughtco.com/what-is-the-fourth-estate-3368058"
The press should also watch the government, and the oversight branches, and all of them should have oversight over the others as a completely closed system that roots out any actions that are may represent impropriety, immoral, OR illegal actions.
Of course, I also believe that OIG should be hounding the Executive constantly, and have the authority and onus to declassify anything classified as soon as possible too. That means that classification stops being a privilege of the Executive, and instead becomes a maintenance item That requires periodic review to reclassify.