By Simon Romero and Michael S. Schmidt

New York Times

RIO DE JANEIRO >> Worried about possible terrorist attacks at the Olympics in Rio de Janeiro, Brazil’s government is working closely with U.S. law enforcement and intelligence services to identify threats and thwart potential disasters at the games.

Despite its notorious battles with violent crime, Brazil has largely been spared the kind of brazen terrorist attacks that have rattled much of the world in recent years, with Brazilian officials long playing down the nation’s vulnerability to homegrown extremism.

But jihadis are calling for mayhem at the Olympics, building on a wave of killings in Europe, the United States and elsewhere over the last year, including the massacre of 130 people in Paris and “lone wolf” attacks inspired by the Islamic State, that has raised broad fears about Brazil’s security preparations for the games.

U.S. officials have been training Brazilian anti-terrorism units on chemical and biological attacks. They are helping to identify soft targets like restaurants, night clubs and shopping malls that are away from well-guarded Olympic venues. And they have been working for many months to train Brazilian law enforcement and military personnel at large U.S. sporting events, including at the Super Bowl in February.

The cooperation marks a notable thaw in ties after the anger in 2013 over U.S. surveillance of Brazil’s political leaders by the National Security Agency. And the shift came into sharp relief last month, when Brazilian investigators revealed that the FBI had helped them identify and track several of the 10 men arrested on suspicion of planning attacks for a Brazilian Islamist militant group called the Defenders of Sharia.

“The Americans are playing a key role in homing in on areas that we need to examine,” said Rafael Brum Miron, a prosecutor in the southern city of Curitiba. “I don’t know how the FBI got their intelligence, but it turned out to be a very valuable lead.”

Fears of terrorism are common before any Olympics. But the frequency of recent attacks around the world — and Brazil’s relative inexperience in grappling with terrorism — has led to a sense of urgency in Rio.

For weeks, the Islamic State has been translating its core propaganda into Portuguese and advertising that it needs Portuguese speakers, in what analysts fear is an attempt to recruit and create a network in Brazil to strike around the Olympics.

Jihadi outlets have been increasing calls for attacks. On July 19, a channel titled “Inspire the Believers!” on Telegram, an encrypted phone app, advised that “Lone Wolf from anywhere in the world can move to Brazil now. Visas and tickets and travel to Brazil will be very easy to get in sha Allah.”

The channel then went on to offer 17 suggestions for attacks around the Olympics, mentioning American, British, French and Israeli visitors as targets. It noted that attackers could drop “poisons or medicines” into food and drinks, or use “toy drones with small explosives,” according to SITE Intelligence Group, which monitors jihadi communications channels.

The same channel had already suggested taking inspiration from the 1972 massacre of Israeli athletes during the Munich Olympics.

Such messages come on the heels of the founding of a new group in Brazil, claiming to be made up of Brazilians, that pledged allegiance to the Islamic State’s leader, Abu Bakr al-Baghdadi.

About a year and a half ago, the State Department’s Bureau of Diplomatic Security, which has taken the lead in protecting American athletes abroad, expanded its footprint in Rio to begin preparing for the games. The Brazilians have managed big international sporting events before, including the 2014 World Cup. Still, what the bureau initially found was a bit troubling, as it quickly identified several soft spots in Brazil’s security, according to senior U.S. officials.

The Brazilians appeared to have little training in how to deal with attacks involving biological or radiological materials. Brazilian counterterrorism operations also seemed to lack enough agents, while security experts argued that legislation to detain and prosecute suspects on terrorism charges lacked teeth.

The United States offered training to the Brazilians, who were more open to U.S. help than from recent Olympic hosts like Russia and China. Dozens of Brazilian officials, law enforcement officers and military personnel flew to the United States. Several attended events like the Super Bowl and the U.S. Open golf tournament to observe how the United States manages security at such high-profile venues.

Still, some U.S. officials worried that Brazil was not taking the threat seriously enough. Trying to avoid taking sides in foreign conflicts, including those in the Middle East, has been a pillar of Brazilian foreign policy. Some political leaders here contend that doing so could make Brazil a target for Islamist militant groups.

But the assessment of Brazil’s vulnerability began to change around the end of last year, U.S. officials and Brazilian security analysts said, as the Islamic State continued to show that it could carry out and inspire attacks in different parts of the world.

“The changing nature of attacks around the world and the realization that Brazil is vulnerable with the proximity of the Olympics have been pushing the government to rethink its approach,” said Marcos Ferreira, a scholar at the Federal University of Paraíba who focuses on terrorism in South America.

In March, President Dilma Rousseff signed anti-terrorism legislation that enhanced the government’s authority to arrest and jail people suspected of planning attacks. Human rights groups criticized the law as being too broad, but Rousseff, a leftist who was imprisoned as a youth over her involvement in a guerrilla group resisting the military dictatorship, signed the law despite fears that it could be used to infringe on civil liberties.

“There is increasing awareness in Brazil of the threat of terrorism, and we are pleased that Brazil passed a new counterterrorism law in March,” said Liliana Ayalde, the U.S. ambassador to Brazil. “The legislation has opened up new channels of cooperation between our two governments.”

© 2016 The New York Times Company