Usage of commas and semicolons

Hello.
I have some trouble to understand the sentence below grammatically.
The sentence is from an article of the Economist, a UK's newsmagazine.

Mr Netanyahu lays particular stress on Israel’s claimed need, if a Palestinian state were to emerge on the West Bank, to retain a military presence there; neutral foreign forces, provided by NATO, as suggested in previous negotiations, would not suffice.

This sentence contains some commas and one semicolon; I want to know how they are working.

First, the semicolon. I learned that semicolons are used to divide two independent clauses and not used between independent clause and subordinate clause such as if-clause and then-clause. I also learned, however, that semicolons can be used as an alternative to commas when many commas can make the sentence complex and confusing.
In this case, is the second rule applicable so the semicolon marks the end of the if-clause?

Second, the first comma in the sentense, the one just before "if". Is this a so-called appositive comma? In other words, does the part from "if" to the end of the sentence give the concrete description about "Israel's claimed need"?

I would appreciate if you can decide whether my understanding is right or not, and give some pieces of advice if it is wrong.

Thank you in advance.