Did KGB spies operating in America during the Cold War had instructions to wage guerrilla warfare and assassinate political targets in case the USSR and NATO went to war, as shown in 'The Americans'?

Like the infamous Facebook relationship status: it's complicated.

First off, you need to understand there were different kind of spies operating under the KGB (civilian intelligence) and the GRU (military intelligence).

There were locals recruited either for money, ideology, by blackmail or deceit (thinking they were actually working for Sweden, CIA, FBI, etc. Like in the show).

There were people who grew up in the west, and decided to immigrate to USSR, were recruited and sent back.

And there were operatives: they were agent handlers, responsible for communications, there were assassins, saboteurs and others.

The show "the Americans" is a work of fiction, and the type of agents it shows (living as locals, gathering Intel, running agents and assassinating) are impossible. In the real world you need different agents, with different expertise for each of these.

Most if the data on soviet agents is still classified, but from what we do know, local agents (as seen in the show) were only used to gather intelligence. For example, during WWII the soviets had several high ranking spies in Germany, but there are no known acts of sabotage they performed.

And in case of sabotage/assassinations usually professionals from USSR were brought in. For example special forces soldiers brought in via submarines or as tourists.

Not much known in Soviet spies specifically in the US and other NATO countries, so I'm also basing my answers on operations in other countries (south america, middle east, etc.)

TL;DR No.