The air is highly charged in Portland even before nightfall.
Almost everyone walking in the city centre streets is wearing a helmet. We pass one corner and someone is putting shin pads on.
Fresh graffiti is going up on another corner. This doesn't feel like a protest limping into its 55th night.
Federal officers sent to restore order in Portland seem to have poured petrol on disorder.
Their refuge is the federal courthouse which is surrounded by a metal fence.
As night falls the crowd of protesters grows outside. The atmosphere intensifies.
Protesters shake the metal barrier. One man attempts to break it with a saw. There are regular loud bangs as fireworks are thrown at the building.
Inside, federal troops observe through broken windows - some windows are shattered, others have holes in them.
It's not clear whether they've been broken from the outside or the inside. They're so high up it's hard to fathom what could have been thrown that high to do such damage.
The first tear gas was fired fairly early and seemed to come from nowhere.
Some demonstrators, now well-versed at this, kept low as the air clouded.
There are cries and coughs as people begin to choke and struggle to see.
We retreat to put gas masks on as the tear gas stings my throat and eyes. We didn't anticipate needing masks so early in the night.
Many of the protesters come well prepared and stand firm.
Rubbish is thrown and set on fire. It's at this point we see the first federal agents.
The response is fast and intense. Dozens of officers emerge from the courthouse dressed head to toe in black armoured uniform.
They're pointing weapons at the crowd and firing rubber bullets. Tear gas fills the air along with the sound of loud bangs. Those in gas masks now run too, the threat of being hit by a rubber bullet is quite frightening.
Largely peaceful protests have been a nightly ritual since the killing of George Floyd in police custody in May.
But violence has escalated and crowds have grown since federal troops arrived in Portland two weeks ago.
People who were protesting racism and police brutality in support of Black Lives Matter are now protesting the very presence of federal agents in their city.
So many of the protesters are tooled up in armour and face masks. It's hard not to look militant, like the anarchists Donald Trump describes.
I stop to talk to demonstrators in a bid to put identities to some of these faceless people.
Two white women in their mid-20s tell me they've only joined the protests in the last few nights. Employed locally, one works as a massage therapist, the other in demolition.
"We wished we'd joined the protests earlier," one says.
I ask if the violence is undermining the movement here.
"We're just hurting a building. Everything about that can be fixed. Buildings don't have feelings," one replies.
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The other says: "They're supposed to keep us safe. I'm just here to stand for what is right, which is not what they represent."
One 38-year-old black man tells me he's been protesting four nights a week for two months.
I ask him how long he'll go on.
"'Until somebody listens to us. We're fed up. We don't want to wait for another person to be killed on the street. Something needs to change.
"For an officer to kill someone in broad daylight. I don't give a damn. That attitude needs to stop. I don't believe in violence at all but unfortunately you've got to make a noise."
Videos have emerged of protesters being taken away by camouflaged troops in unmarked vehicles in Portland.
Two justice department inspectors general have announced investigations into the improper detention of protesters here.
Meanwhile, Mr Trump has pledged to send a "surge" of federal troops to other Democrat-led US cities to help combat crime. Like Portland and Oregon, several mayors and state governors have said they do not want this help.
The election is fast approaching and many say it's hard to separate the president's actions from politics. Actions that have made Portland rage.
The city's mayor has called federal troops an occupying force. The head of Homeland Security said his agents "won't retreat".
It certainly sounds like warfare. And, as the city prepares for yet another night of battle, neither side seems close to backing down.