Aimed squarely and unabashedly at viewers who love soldiers, gore and dinosaurs – as well as dinosaurs goring soldiers – this adaptation of Ethan Pettus’s 2017 novel is deeply repetitive but weirdly watchable. Although shot in Australia with a mostly Australian cast sprinkled with a few American actors, it’s supposed to be set in Vietnam in the late 1960s as the US armed forces take on the Viet Cong.

But there are other forces to contend with, and we don’t just mean covert Chinese or Soviet operatives, although the latter do feature significantly here. It turns out a nefarious scientific experiment by one of the aforementioned factions has accidentally ushered a whole army of dinosaurs into the jungle and they’ve begun gaily munching their way through anyone who gets in their way. When one squad of Green Berets go missing, Colonel Jericho (Jeremy Piven, hamming it up lustily) assigns the elite Vulture Squad to go in and find out what happened. The troop are led by square-jawed Sgt Ryan Baker (Home and Away veteran Ryan Kwanten) who commands your typical assortment of grunts representing, as we’ll soon see, a range of intelligence quotients that make them ill-equipped to cope with the challenge they are about to face.

At least they’ve got some firepower, which means a lot of the dialogue and the background music is drowned out by gunfire. Speaking of music, the production has shelled out for some very on-the-nose needle drops including Creedence Clearwater Revival’s Run Through the Jungle and Fortunate Son in case anyone forgot this is meant to be the 1960s. The money might have been better spent on decent VFX because the dinos, especially when seen in the full-daylight sequences, look pretty plasticky. The representations of disgorged innards of the prehistoric beasts are more convincing, and there’s a cheerful cheesy gleefulness that motors the movie along.

• Primitive War is in UK and Irish cinemas from 28 November.