FOZ DO IGUAÇU, BRAZIL: On a chilly morning, with a breeze blowing in from Paraguay, customs officials occasionally stop and search vehicles crossing Brazil’s busiest border point, looking for contraband.

Most passengers are poor Brazilians, carrying electronics they were commissioned to buy duty-free over the river in Paraguay’s Ciudad del Este, but there is a more dangerous trade too.
“It’s not unusual to find drugs or arms,” said Leonardo, a tall Brazilian customs official with a few day’s stubble who has been working the bridge for two years. “You start to get an eye for it,” he said.
With just days to go before the Olympics start in Rio de Janeiro, Brazilian security forces have shifted their gaze to an even more amorphous crime: terrorism.
They have increased checks at this border post — where tens of thousands of people cross back and forth every day - and have set up a control room with access to dozens of cameras watching different points of the frontier.
Intelligence officials have long pointed to this border region, home to a sizable Muslim community, as a weak point in Brazilian security.
{{/usCountry}}Intelligence officials have long pointed to this border region, home to a sizable Muslim community, as a weak point in Brazilian security.
{{/usCountry}}With an estimated 500,000 foreigners descending on Rio, the daunting task of monitoring the border area between Brazil, Paraguay and Argentina has come back into focus.