If you require a Bachelor Degree in the PERM petition, it refers to a US Bachelor Degree or foreign equivalent.
USCIS will allow a combination of academic work and work experience to be used in an Academic Evaluation for an H-1B Visa petition, but they do not allow it for PERM / I-140 based petitions.
If the beneficiary has a foreign degree (highest degree is non US Bachelor or Master Degree), then you will need to obtain an Academic Evaluation to show that it is the equivalent to a US Bachelor or Master Degree.
Trusteforte Corp. performs this service and their work is accepted by USCIS. You will want an Academic Evaluation using the EDGE database. http://trustfortecorp.com/academic.html
In the advertisement and recruiting, the acceptance of a foreign degree would be shown in the requirement line as (for example): Bachelor Degree or equivalent in Computer Science. This means that you would accept a US Degree or foreign equivalent. If the requirement reads: Bachelor Degree in Computer Science, this is interpreted by DOL and USCIS that you would not accept a foreign degree equivalency for this position.
In general, a 3 year foreign bachelor degree is not considered to be equivalent to a 4 year US bachelor degree. In this case, you would not be able to require a bachelor degree since the beneficiary does not possess a (4 year) bachelor degree.