This tendency was on show at a meeting at the International Institute for Strategic Studies in London this morning, where Lieutenant General Gérson Menandro Garcia de Freitas, who is Deputy Chief of the Army General Staff, was attempting to answer a question that has defeated better minds than mine: what is Brazil's army for? One if its strategic purposes over the next few years, Mr Gerson said, was to guard the country during these two sporting events.

From whom? The army is clear that it is not a police force, so the general did not mean that it would be guarding against terrorism or backing up military police in subduing Rio's three main drug factions. Does the army think the Americans will pull out of Afghanistan, sneak into Brazil while the nation is tuned in to the World Cup final and annex the Amazon? Might Hugo Chávez, Brazil's close friend and ally, invade Roraima while the women's beach volleyball is in full swing?

Despite this alarming new threat, the army's "strategic priority" in the coming years will be the Amazon. The number of border posts where troops will be stationed will be increased, and still more soldiers will be trained in the art of jungle warfare. Again, this is bizarre. Brazil has not fought over any bits of the Amazon since the scrap with Bolivia over Acre 107 years ago. It is at peace with its seven neighbours in the Amazon, and has been for a long time.

Strangely, this is an area where some politicians on the left and the military are in perfect agreement. Roberto Mangabeira Unger, the minister who oversaw last year's National Defence Strategy, shared the military's interest in using the army for nation-building in the jungle. He also encouraged conscription as a way to break down class divides in Brazil. Such thinking is in tune with the way the military has long thought of itself—a worldview that has led to trouble in the past.

One might expect politicians on Brazil's left to be keen to focus the military's ambition more narrowly: many of them, after all, suffered at the hands of an army with a bad case of mission creep. Instead they seem to encourage it. So Dilma Rousseff, the front-runner in the presidential election—who was tortured by the military regime that ran Brazil from 1964-1985—talks about the need for a nuclear-powered submarine to defend the "blue Amazon" off Brazil's shores from foreign pirates intent on seizing the pre-sal oil fields.

Meanwhile, Brazil's army is busy carrying out real, important, peacekeeping missions in difficult places like Haiti and Congo. This should be what it is for. Only these missions are unpopular back home and seem to have a low priority even within the military.