Clicking a Breadcrumb Link, Trigger Browser Back Button, or Forward?

Background

I have a set of breadcrumbs for a web site:

enter image description here

Question

When a user clicks on these, should I trigger the browser's back button using JS? Back n times? Or should these be regular a tags that move forward.

Note: I'm using a script which adds itself to the a so that if there is no history (a page was bookmarked and gone to directly), then the regular link kicks in. This question assumes that there is history.

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