Wait a moment, as President could, under the law, make the determination if arms should be sold to Iran. Now, you can disagree with that decision (and I did/do), but there was nothing illegal in it. The problem, and the scandel, came from what happened from the profits of those sales. There is a record, and an admission at the time, that Reagan did authorize those sales, but that wasn't illegal. Extremely bad, yes, but not illegal.
The POTUS is bound by the foreign policy mandates passed by Congress. Violating them are an illegal act.
From merriam webster's website,
Main Entry: en·trap·ment
Pronunciation: -m&nt
Function: noun
1 a : the action or process of entrapping b : the condition of being entrapped
2 : the action of luring an individual into committing a crime in order to prosecute the person for it
And this is absolutely entrapment. The scope of the investigation by the OIC was to investigate Whitewater. The original investigator, Robert Fiske, was about to wrap up his investigation in '94 when the GOP threw a hissy fit and insisted on appointing Ken Starr. Starr ILLEGALLY expanded the scope of his investigation to include a sex scandal which began AFTER Starr came in. So if there is no investigation there is no perjury. If Robert Fiske is allowed to finish his work, there is no perjury and no waste of MILLIONS of dollars.