They and Mossad combined know everything about everyone.
The NSA/CIA has nothing on these two agencies.
China sends accent-less English-speaking "journalists", "recruiters" and other legitimate-seeming personnel to the US to supplement their cyber their intelligence. The recruiters represent US contracting companies and show up at military and intelligence job fairs or conferences. The swag they give out contains monitoring equipment (e.g. flashlight key chain with GPS, thumb drives, etc.) The Chinese government obviously can't have US military contractors, so they send operatives as immigrants to the US. The operatives then have children who are natural US citizens. The kids go through the US school system while being indoctrinated into Chinese intelligence. When they graduate high school or college, they "visit family" or "study abroad" in China, where they're trained. They return to get jobs with US intelligence or military, often as linguists/translators, as they "learned Chinese from their first generation immigrant parents". They're completely integrated into American life, like the Soviets were during the cold war.
Mossad, on the other hand, sends "students" to work at malls (selling Dead Sea salts, etc.) near military bases to test operational security leaks. They target low-ranking personnel who provide seemingly innocuous information about training and deployments that when coupled with information from other military members or intelligence sources give a pretty comprehensive view of what units are up to. This serves the larger purpose of letting Israel know how much the US shares with or whithholds from them regarding military operations, how well US personnel are trained in operational security,