Just caught the tail end of a 1957 B movie on UK Freeview 70 (The Horror Channel). Film called 20 million miles to earth.
Interesting to see the equipment deployed in Rome to fight against the creature, Chaffees were no surprise, given that they were led by a US general, but the surprise was bren carriers (looked to be towing 6 pdrs, but might have been US 57mm).
Did the US use bren carriers?