1)
What fire will Hashem kindle?
1.
Malbim: It is the fire of war. He kindled it at once all around ? it spread to all of Bnei Amon ? "u'Vnoseha ba'Esh Titzasnah" (Yirmeyah 49:2). Since their idolatry (Molech) is served with fire, it teaches that the fire is not from it.
2)
Why does it say "bi'Sru'ah"?
1.
Radak: So it says "v'Hishmati El Rabas Bnei Amon Ter'uas Milchamah" (Yirmeyah 49:2). Malbim - they blow Ter'uah in war.
3)
What do we learn from "b'Sa'ar b'Yom Sufah"?
1.
Radak: The strength of war and quick capture is compared to a storm wind. Sufah is Sa'ar; the matter is repeated in different words.