When espionage activities and secret operations have been leaked before their implementation, then the agents concerned and those whom they are in contact with must be put to death.

用间的计谋尚未实施，就被泄漏出去，间谍和知道机密的人都要处死。

youdao

Some of the commercial activities were a cover for espionage.

有些商业活动是为间谍活动提供掩护。

《牛津词典》

U.S. counterintelligence resources are already being overwhelmed by the multitude of Soviet espionage activities.

CENTERFORSECURITYPOLICY: Center For Security Policy

If a case can be made that Felix Bloch engaged in espionage activities for the Soviet Union, the United States government must prosecute him.

CENTERFORSECURITYPOLICY: The Felix Bloch Affair: Assessing The Damage To US Security

The cyber espionage activities described by the researchers are cyberspying techniques employed by the U.S., Israel and a number of other countries, cybersecurity specialists said.

WSJ: Cyberattack Hits Iranian PCs