Participle Phrase Punctuation

Ex.

Molotov sees the West as deceitful, breaking its promises made at the previous meetings two years ago, which had united the three Allies against Nazi Germany.

Q.

Why is the "breaking its promises made at the previous..." part set off by commas?

Participle phrases use no comma if it's describing a noun that immediately precedes.
They need a set of commas ONLY if it's in the middle of a sentence.

I wonder why there is a comma after "deceitful."

Thanks in advance.