In a scene that was bizarre even for these times, the Democratic mayor of Portland was himself teargassed by these agents when he met with the protesters outside the federal courthouse.

The concerning political context to this deployment is President Trump's long-running battle with the nation's Democratic mayors and governors. Since the outset of the pandemic, the president has blamed part of the devastating health outcomes and incredible civil unrest on the United States' urban Democrats and the Democratic governors of conservative states. In the starkest expression of this, he infamously issued calls on Twitter to "LIBERATE" Democratically-governed states from the lockdowns we can now see were keeping the pandemic at bay.

Speaking on Fox News as images of the chemically irritated mayor of Portland played, the president's senior adviser Stephen Miller labelled these Democratic leaders successionists - even as the president leverages federal departments to protect statues celebrating successionist Confederates.

On Thursday, the White House announced a "surge" of hundreds more of these federal agents into Kansas, Chicago and Albuquerque - all Democratically-governed cities.

These political through lines have earned the agents in Portland the moniker "President Trump's little green men" - a reference to Vladimir Putin's deployment of unidentified Russian troops during the Ukrainian crisis in 2014.

The Democratic Senate Minority Leader, Chuck Schumer, said of what's happening in Portland: "It's like a third-world despotic country. You pick up someone, no identification, drag 'em somewhere and he doesn't even know, or she doesn't even know what's [going on]."

While he's not incorrect, this is also not dissimilar to what US special forces do in "third-world despotic" countries. Rather than simply importing these tactics from bogey foreign powers, the Department of Homeland Security and other federal agencies are repatriating them.

By all appearances, Portland has been a sandbox where the legal limits of federal law enforcement and the bounds of a politicised Department of Justice under Attorney-General William Barr have been aggressively probed. If the aim of the Portland experiment has been re-establishing order, it's quite clearly failing. Protests in the city now appear to be growing larger than at any point since the death of George Floyd.

If the aim was division and the spectacle of the "president of law and order" tackling the forces his campaign say will be unleashed by a President Joe Biden, then we'll know after the election how well it worked.

But while there is so much focus on the ground skirmishes between police, federal agents and protesters, above the clouds of teargas and smoke from fireworks and burning police precinct headquarters, there has been another federal response to these protests across the United States since their outset that cuts to their very core: A distinctly modern and militarised one.

In late May this year, a US Customs and Border Protections predator drone conducted an operation over protests and riots in Minneapolis. The unmanned aircraft used is the same model as those that have attacked military targets in the Middle East and have immensely powerful surveillance capabilities.

Days later, the FBI and the US National Guard deployed RC-26 spy planes over Washington DC and Las Vegas. On the same night, the FBI also sent up a small plane over DC that has been equipped in the past with "dirtbox" technology designed to mimic a cellphone tower, tricking phones into connecting to it, and then collecting data from them. There's further evidence still that more of these planes and some helicopters conducted operations above DC with their identifying information switched off.

In late June, Arizona police used drone footage to arrest three protesters for blocking traffic and using chalk to graffiti a street crossing.

In a time of such unprecedented protest against police brutality and the militarisation of police, it appears as though federal and local agencies are testing the bounds of bringing their domestic capabilities in line with modern conceptions of militarisation.

To understand how a police force with fewer guns, less riot gear and no chemical irritants could be as militarised a force as it was with them, it's helpful to invoke the modus-operandi of the initial pushes to equip American police with modern military hardware: Shutting down protests before they had the chance to spread nationally.

Using blunt force was ultimately deemed to be the most effective strategy for security forces to quell unrest in the years of national upheaval in the 1960s and 1970s.

Increasingly in the social media age, the ability to record, stream and share the use of these heavy-handed tactics has meant instances of police brutality can inspire national and even global protests in near real-time.

So, for a theory of policing protest that prioritises containment, it is phones and communication that are as pressing a threat as bodies and voices. This means technology can allow forces to strip back the visual and grating signifiers of traditional armed forces - like the little green men - and to develop a force posture which is felt, but not seen. One that could either turn protesters' data against them, or merely by virtue of that threat, chill their expressions of dissent.

There are already myriad guides online for how to protect your data while protesting. The most effective way: to leave your phone at home.

The coalescence of mission creep in federal law enforcement, a politicised US Department of Justice and the seemingly immense collection of data during these protests is a concerning one. What's happening in Portland will have implications for how democracies respond to protests.