Initially Babel-17 is thought to be a code used by enemy agents.
You let an enemy agent go back to the French?
It might think he was some kind of enemy agent.
At any rate, the enemy agent was now definitely suspicious.
The idea of doing a deal with an enemy agent was no longer unthinkable.
On the other hand, she might be an enemy agent.
Most of the books had been captured from enemy agents or organizations.
Italian or Israeli she was certainly an enemy agent of some kind.
One had to face the fact that this girl was an enemy agent.
One thing we didn't have to worry about in this war was enemy agents.