Sending military helicopters of any kind to harass a crowd is way, way over the line.
https://www.justsecurity.org/78053/the-national-guard-at-lafayette-square-and-the-january-6th-attempted-insurrection-fixes-for-the-fy2022-ndaa/
August 31, 2021
While the Trump era exposed weaknesses in many U.S. institutions and resulted in the proliferation of reform proposals from organizations like ours, relatively little attention has been paid to much-needed reforms to the domestic deployment of the National Guard. The brutal crackdown on nonviolent demonstrators on June 1, 2020, at Lafayette Square and the attempted insurrection at the U.S. Capitol on January 6, 2021, provide important lessons about how and when the National Guard is (or is not) deployed domestically, its command structure for domestic deployment, and the Guard’s legal authority when it acts. [snip]
In response to the widespread protests following the murder of George Floyd last summer, former-President Trump deployed both the D.C. National Guard and thousands of out-of-state National Guards members into Washington, D.C. to police protestors. In doing so, the administration performed an end-run around the Posse Comitatus Act, which prohibits the use of federal military forces inside the United States for law enforcement purposes unless doing so has been expressly authorized by Congress or the Constitution.
Mentioned in the above:
https://www.nbcnews.com/think/opinion/trump-barr-used-loophole-deploy-national-guard-u-s-cities-ncna1236034
Aug. 7, 2020, 8:30 AM UTC
By Sen. Tom Udall and Rep. Jim McGovern
The Posse Comitatus Act bans the use of National Guard units for law enforcement only when they are federalized, meaning they are brought under the command and control of the president. When National Guard units are operating in so-called hybrid status — serving federal missions funded with federal dollars but under state governors' command and control — they are not subject to the act and therefore are able to perform law enforcement functions, like searches and arrests.
Congress has limited the activities the National Guard can perform in hybrid status, but it does allow it to perform training exercises in this formulation. Barr twisted this provision to enable the rogue deployment in Washington from 11 states.