Here is my "operational experience," from the perspective of an activist working with journalists:
The location is an EarthFirst! training camp. The objective is to train a mixed group of locals and out-of-town activists in various blockading techniques (aerial blockades, sleeping dragons, etc) and, at the end of the week, non-violently blockade access to a particular industrial site as a part of a larger, regional campaign against the company that owned and operated the site.
There were two independent journalists present. One was a documentary filmmaker and the other was a still photographer. Both were sympathetic to the goals of the activists and had some experience working closely with activist groups.
The action failed because the journalists did not follow the security rules that everyone was supposed to abide by.
Security was managed as follows:
-Everyone used pseudonyms, or "forest names," which are one-time-use names, to be used only at that training camp and during the action. Outside of the people you arrived with, you didn't know anyone's real name. This is useful in case anyone is arrested and chooses to cooperate with police; it limits the damage by restricting the amount of information that people know about each other. Pseudonyms are also useful because they limit what undercover officers or informants can learn.
-Only a small core of experienced activists (five to eight people), who had longstanding histories working together, knew what the target was. This same small core planned the logistics for the training camp. Everyone knew the name of the company we were protesting (naturally), but our training camp was located within a three hour driving distance of dozens of targets owned by the company.
-Attendees were sorted by their comfort level with risking arrest. People self-sorted by "red" (you will be arrested in this role - these were the people who were to lock down in a sleeping dragon or sit in an aerial blockade), "yellow" (you may face arrest - a direct support role), and "green" (low risk of arrest - you will be located at a site next to the action, on public property, holding protest signs).
-Once we were all sorted by self-selecting risk level, the "red" and "yellow" groups were subdivided into two compartmentalized training groups (so there were both "red" and "yellow" people in each of these two training groups), and the "green" group formed a third training group. We were told not to tell other activists outside of new training groups what we doing inside of those groups. Each group was led by one to two activists from the small experienced core. Only this small core of experienced activists had the whole picture; they were the single point of failure between the compartmented groups and only they knew the target location and the time of the action.
-As I later found out, during the action, one training group was learning aerial blockading, and the other was learning how to form sleeping dragons. The third group was learning how to support the first two with media, logistics, and jail support. I was in one of the two blockading groups.
-To thwart the possibility of audio surveillance via cellphones, everyone would put their phone in a plastic bucket at the beginning of a training session or discussion. This bucket would then be placed well out of earshot, but where everyone could see it. Since we didn't know each others' real identities, there was no trusted person who could hold all of the phones. Keeping the bucket in plain sight solved this.
-The aerial blockading equipment to be used on the day of the action was kept off site. Only activists from the trusted core knew about this offsite location. We practiced with identical equipment at the training site. This was done to thwart any attempts to steal, destroy, or otherwise sabotage the equipment. The operational equipment was brought on site on the morning of the action, as we prepared to depart.
-On the morning of the action, everyone woke up at 2am, grabbed their gear and staged with their training team. Each team piled into several cars with a designated driver and navigator. Everyone was instructed to turn off their cell phones. The trainer activists from the trusted core handed a sealed envelope to every driver. We were to drive in convoy up the highway, behind a lead vehicle, until we passed a particular exit number. Then we could open our envelopes. They contained the address of the target, a hand drawn map of the area (to include some terrain features), and a separate street map with our route to the target. Every vehicle had a different route to the target, in order to throw off any vehicle surveillance. The idea was to arrive just up the road from the target at about the same time, and then drive in and "hit it" by rapidly setting up our two blockades.
-What's known in activist communities as "security culture" was followed. People didn't discuss their private lives, past actions, or illegal activity. No one used substances at the site, illegal or otherwise (break one law at a time, don't impair your judgement).
These security measures may seem elaborate, but keep in mind that this event was open to the public and advertised in advance, as a part of a very public campaign against a fossil fuel company that involved legal protest, legal advocacy through the courts, organizing popular support through NGOs, as well as non-violent direct action. While the planned action would be illegal (trespassing), this was not an invite-only event for a small clique of activists. It was a large gathering of unconnected environmental activists with various risk tolerances, ages, and political views. Everyone was aware that an undercover officer or informant could easily be present, and we all conducted ourselves as though anyone not previously known to us could be an informant. There wasn't paranoia or an accusatory atmosphere, we just kept our mouths shut about personally identifying information and the details of what we were learning in our training group. As it turned out, there were in fact two undercover police officers present at the training camp.
Security failed for two reasons:
One of the "core" experienced activists told the still-photog journalist the exact target location, the day before the action. The activist trusted the journalist and must have figured that it was fine. As it turns out, the journalist was trustworthy, insofar as they weren't an informant, but their opsec judgement was poor. One of the two undercover officers elicited the target's location from the journalist by offering to help them buy extra camera memory cards on the day of the action (typically, on the day of the action, one person is employed as a runner to get the memory cards from the photog journalist at the action, to a safe legal space like a nearby church, where those photos can be uploaded to the internet, since the photographer is at risk of arrest and may have their equipment confiscated at any moment after the cops arrive on site). The journalist told the undercover police officer the name of the nearest town where they could buy camera memory cards on the day of the action. This was enough information for the officer to learn the location of the action, in advance.
Now, most of the activists at this training camp suspected that the two undercover cops were, in fact, cops. They acted like cops. One of them wore Gates boots and Oakleys. It was not a big mystery. However, no one expelled them or publicly accused them, because left-wing activists have learned the hard way that runaway snitch witch hunts can do far more to damage to movements than actual informants. Fear is deadly, so there is a cultural norm against accusation, unless there is proof. Otherwise, people share their suspicions in private, with trusted friends, and then they ice the suspected cop out of sensitive conversations. Since the two journalists were out of the loop, they didn't learn that these two guys were probably cops. Since they didn't have experience as activists themselves, they didn't know to be suspicious of these two undercovers (the proof came later when their identities as police officers was revealed in legal discovery, during the trial of another activist who was arrested at a different action in course of the same campaign).
The second journalist, the documentary filmmaker, drove his own car to the action site on the morning of the action. He asked one of the "core" trainer activists where to go on the morning of the action (so, two in the morning), and he was told the location. However, he was also told to follow any of the other activists' cars to the target location, and to turn off his phone. He ignored that advice.
Instead, he punched the target location into his iPhone and drove directly to the target site. Since everyone else was driving along their unique, circuitous routes as specified in their envelopes, in the hopes of confusing following vehicles and converging at the same time, the journalist got to the target site before anyone else. He got there forty minutes early.
When we all arrived at our convergence position and drove in convoy the remaining mile to the target, we found that the cops were already at the target site. Within minutes, they had ample re-enforcements and going through with the action proved impossible. Since we didn't have a chance to deploy, we weren't arrested, but the action failed.
In addition, the journalists were explicitly asked to get consent before filming anyone at the camp, but they chaffed at this and had to be asked not to film on several occasions.
That's my experience.
Edit: I realize that this post may come off as a little hard on journalists. I'll just add that documentary filmmakers have made some incredible short films about this kind of activist work, like this one:
It's just important to remember, as a journalist, that the people around you may have good reasons for being cautious.