Agents are the aorta of human intelligence operations.

Intelligence officers recruit individuals, referred to as agents, to spy for their particular service. Agents are targeted for recruitment based on their ability and willingness to use access or relationships to provide valuable information on matters of concern.

Later, I'll explore what a new report by Britain's Parliament tells us about British intelligence agents. First, however, here's a basic hypothetical example of how an agent might be recruited.

The MI6 (Britain's foreign-focus intelligence service) station in Vienna learns that a mid-ranking SVR (Russia's civilian foreign intelligence service) officer, "Lavrentiy", will be traveling from Moscow to attend an IAEA summit in the Austrian capital. MI6 knows Lavrentiy has a drinking problem and might be disillusioned: he's been passed over for promotion three times.

Recognizing that Russian spies might be monitoring Lavrentiy and MI6's Vienna station during the trip, MI6 headquarters send a mid-ranking MI6 officer, Max, from New Delhi to Vienna. Max knows that Lavrentiy will probably tell him to get lost, but also that this opportunity can't be passed up.

Max knows the hotel where Lavrentiy is staying but doesn't approach him there or at the IAEA summit: doing so would be too predictable, too dangerous.

Instead, with the help of others at the MI6 station, Max acquires a fake taxi and follows Lavrentiy as he engages in a post-summit Vienna bar crawl. At 10 pm, Max is notified that an intoxicated Lavrentiy seems to have had his fill: the SVR officer might be a drunk, but he recognizes he is attracting too much attention.

This is the moment. As Lavrentiy walks outside, Max, disguised in face and physique, pulls up in his taxi. In fluent German, Max asks Lavrentiy where he wants to go. Informed, they start driving. One minute later, Max asks Lavrentiy, "What phone do you have?"

It's an odd question and Lavrentiy doesn't answer.

Max cuts to the chase and changes from German to Russian: "I work for the British government. In the interest of Anglo-Russian relations, would you be interested in helping us answer certain questions?"

Lavrentiy tells Max that the Briton's mother engages in extracurricular activities with animals and promptly vacates the car.

But six months later, a similar MI6 operation with a different SVR officer succeeds. This time, the Russian appreciated the MI6's officer's knowledge of his country's composers. Specifically, "Igor" liked how "Jennifer" used Dmitri Shostakovich's struggles against Soviet oppression as a semi-teasing metaphor for Igor's own struggles in Moscow and better opportunities in London. Along with some hard cash promises, Igor agreed to become an MI6 agent. He was quickly given instructions on how to pass over intelligence surreptitiously and the bank details where his MI6 payments will be held under a cover name.

Lavrentiy, however, has been permanently blacklisted for promotion. Sure, he reported the British approach to his bosses, but they think he's lying. Good chekists, they know that traitors are always everywhere and always plotting.

Hypothetical scenario over.

Why does this matter for reality?

Put simply, because it illustrates that agent recruitment is very difficult, dangerous, and unpredictable.

This is relevant in light of the British Parliament's Intelligence and Security Committee 2016-2017 report. As I've explored over the past couple of days, the report offers some interesting takeaways. However, it also includes some rare references to British intelligence recruitment of agents.

First off, the ISC draws partisan distinctions between MI5 (Britain's domestic-focus spy service) and MI6's respective use of agents.

When it comes to MI6, the ISC is all for agent recruitment. In deferential language it says, "as [MI6] pointed out that the benefits provided by agents’ intelligence can be very substantial, meaning even large agent-related costs can represent good value for money." Indeed, MI6 told the ISC that the "amounts that agents receive will range from hundreds of thousands of pounds to zero."

But when it comes to the domestic-focused MI5, the ISC suggests that agent running "clearly has scope to be highly controversial."

Here, we see the political tenor to the ISC's reporting: Made up of elected members of Parliament, the politicians want to ensure they are on the record should MI5 ever recruit an agent who turns out to be engaged in continuing acts of terrorism or serious criminality.

This is a cheap shot.

The parliamentarians know that MI5 could not save lives without agents. A senior MI5 officer told them as much: "I don’t want to talk about agents without acknowledging the fact they take risks for us, they do brave things for us, they are the intelligence collection asset that we could not operate without. They give you insight that technical intelligence cannot give."

Yet for the politicians, because MI5 agents are mostly domestic and MI6 agents mostly abroad, the potential risk factor for betrayal is far more politically toxic.

Of course, for foreign agents, the risks are also very great. The ISC report outlines that, for those who serve long enough in dangerous environments, MI6 operates a dedicated resettlement team to provide them with a new life.

Still, whether at home or abroad, agents are the crucial element to giving intelligence services that which a satellite or intercepted communication cannot: a key to the heart and mind of foreign governments and terrorist organizations. MI5 deserves more political respect.