There are plenty of Vietnam memoirs and films but surprisingly few novels about the war, and none of them could be called exceptional or definitive. In his first full-length novel for nine years, Denis Johnson sets out to fill the gap with a lengthy work that stretches from 1963 to 1973 with a coda in 1983, also takes in the Philippines, Japan, Hawaii, Thailand and Malaysia, and has a suitably sizeable and international cast.

The implicit aim is to do for the conflict what Thomas Pynchon’s monstrous Gravity’s Rainbow did for the Second World War, yet what seems to haunt Tree of Smoke is a far more slender offering: Graham Greene’s The Quiet American, still pre-eminent in Vietnam fiction, although it dates from the Fifties when France was the imperial power under siege. Johnson too has a protagonist, Skip Sands, who is an American spy, and references to Greene’s novel pop up regularly.

Adding to the novel’s derivative feel is the influence of Joseph Conrad’s Heart of Darkness (already adapted to Vietnam in the film Apocalypse Now). Skip owes his job to his uncle, a veteran CIA operative. Though ebullient and gregarious, Colonel Sands resembles Conrad’s Kurtz in that his eccentricities – writing a rambling, heretical paper on intelligence strategy, getting film of a college football game sent from the US as inspiration for taking defeat with dignity – lead colleagues to question his sanity. Just as Kurtz carved out a private ivory empire, so Sands ‘sort of borrows’ a platoon and a chopper for two years as he sets up a helicopter landing zone at Cao Phuc, falling into disgrace when he loses the entire platoon in the Tet Offensive.

Around this pair swirl all the other characters. James Houston, an infantryman assigned to a Recon squad, is part of the Colonel’s quasi-private army at Cao Phuc; his brother William, the hero of Johnson’s debut Angels, is seen here in his younger days as a sailor. Jimmy Storm, a gung-ho spook who becomes increasingly prominent as the novel advances, is one of the Colonel’s disciples.

As Skip Sands completes his training in the Philippines – where he witnesses the grisly assassination at his colleagues’ behest of a dotty Catholic priest suspected of Communist links – he begins an affair with Kathy Jones, a Seventh Day Adventist nurse, and the novel’s only significant female figure. When Skip relocates to Saigon, he stays in a CIA villa where Nguyen Hao caters for his needs. (Hao is also the contact for Viet Cong double agent Trung Than, relaying the information he produces to the Americans.)

Tree of Smoke gives oddly little sense of Vietnam as a military conflict. The Tet Offensive scenes are tantalisingly good, but this is the only time combat is depicted; Johnson’s subject is what war does to men, not war itself, and he typically observes soldiers and sailors in bars rather than on the battlefield, displaying the remarkable ear for stoned guy-talk evident in his previous fiction.

Spying occupies the centre stage vacated by fighting, in two distinct forms: the humdrum business of extracting information and bumping off real or imagined enemies, as practised by Skip or Jimmy; and the exotic version practised by the Colonel, involving abstract theoretical mumbo-jumbo, strange and probably useless secret files he entrusts to Skip, and an obsession with the Viet Cong’s network of tunnels. It’s hard to get a grip on how his enigmatic activities relate to the wider war; and hard, too, not to see the novel’s emphasis on intelligence as a form of evasion.

Reminiscent of Pynchon’s titular symbols (V partly signifying the atom bomb and Gravity’s Rainbow partly signifying Hiroshima), the tree of smoke is a phrase the Colonel takes from apocalyptic lines in the Song of Solomon, and suggests the kind of sacrificial or penitential rite Jimmy submits to, surrounded by tribal people, in the penultimate scene. Skip glosses its meaning for his uncle as a drive to ‘unfold himself like a dark wraith and take on the whole Intelligence Service’; while in the Colonel’s infamous article, the words (‘Tree of Smoke – note similarity to mushroom cloud: Hah!’) prompt the positing of a ‘final step: to create fictions and serve them to our policy-makers in order to control the direction of government’.

As with Pynchon’s V-rockets and bombs, the Tree of Smoke is hence both a metaphor for the war machine’s fabrications and covert grand design, and a metaphor for the book it names. In the latter role it’s all too accurate, as Johnson’s novel leaves little lasting impression once read: big moments are few, and there’s frustratingly little sense of what all the toing and froing is meant to add up to.

Johnson’s expertise in dialogue and atmosphere means it works on the level of the individual scene, suggesting that his natural form is the short story; but when it comes to overall structure and main plotlines, Tree of Smoke is tellingly dependent on reworking other fiction. It takes Greene’s tale and updates it from the Fifties to the Sixties; borrows Kurtz from Conrad’s novella and places him at the centre of an enormous, polyphonic novel; mimics Pynchon’s multivalent symbols, and transfers his cast of psychic casualties wandering across Europe in 1944–45 to South-East Asia twenty years later. Although it’s by no means a disaster, there’s too much that’s second hand, and too much that seems easily cuttable. The great Vietnam War novel is still to be written.