I admit it: I'm baffled. Why would this be a US security issue for US citizens? The entire point of the APEC card for a US citizen is to gain expedited entry into OTHER countries in the covered region. Ostensibly for business/economic purposes.
Is the issue that the US citizen applicant needs to be "vetted" and USDHS is the appointed agent for doing the vetting, on behalf of the other APEC countries--who will then presumably take USDHS approval and issuance of the APEC card as de facto evidence that said approved US citizen is OK to admit under APEC?
I presume that acceptance in to Global Entry, NEXUS, and/or SENTRI all qualify as TTP's.