IELTS Grammar: passive with 'being'

A student asked me about the use of 'being' in the following sentence.

"There is a danger of nuclear weapons being obtained by terrorists."

Here's my (updated) explanation:

• First, imagine that the simplest version of this sentence is this: "There is a danger of x" (in which x is a noun).
• Now we can consider "nuclear weapons being obtained by terrorists" as a big noun phrase.
• The "being obtained" part of this phrase can be called a passive gerund. It is not a verb or verb phrase, so the word "are" (are being) is not missing and cannot be added.

Note: When we use the phrase "there is a danger of...", there is a future implication. So, "there is a danger of x" means "there is a danger that x will happen".

Therefore, our sentence really means this:
- There is a danger that nuclear weapons will be obtained by terrorists" OR
- There is a danger that terrorists will obtain nuclear weapons.

Thanks to Morteza and Oleg for pushing me towards a better explanation!