On Wednesday, Iranian president Mahmoud Ahmadinejad touched down in Brazil for his first state visit to the South American nation since 2009. The ostensible reason is to attend the U.N. Conference on Sustainable Development, a high-profile gathering of more than 100 heads of state taking place in Rio de Janeiro. But high on Ahmadinejad’s priority list is an important bit of diplomacy: reinvigorating the once-robust ties between Tehran and Brasilia. For Iran, Brazil is a potential economic lifeline in the face of mounting international pressure.

Ahmadinejad has his work cut out for him. Several years ago, when Ignacio Lula de Silva presided over the Brazilian government, Brasilia ranked among Tehran’s strongest partners in Latin America. Over the past year-and-a-half, however, relations between the two countries have cooled considerably, much to the chagrin of Iranian officials.

The turnaround is attributable to Lula’s successor, Dilma Rousseff, whose foreign policy is considerably less ideological than that of her predecessor. A former women’s rights activist who spent time in prison, Rousseff has made a point of distancing Brazil from Iran since taking office in January 2011, citing Iran’s troubling human rights record. Earlier this year she rebuffed Ahmadinejad when he wanted to make a state visit, and it’s unclear she will grant the Iranian president an audience this time out either.

Yet if these developments suggest that Brazil is rethinking the prudence of partnership with Iran, the reality is that trade ties between the two countries are still active. Indeed, Brazil represents Iran’s largest trading partner in the region. The concern then is that in the future, the Rousseff government could well find it advantageous to renew closer ties with Iran.

Iran hopes to spur just such a shift, and Ahmadinejad’s Latin American tour has a great deal to do with courting the Rousseff government. If Tehran can thaw relations, then perhaps access to the Brazilian economy will help Iran weather sanctions now being levied against it by the West for its nuclear program.

But Iran is also solidifying its presence in Brazil by other means. For instance, along with its terrorist proxy Hezbollah, which maintains a significant presence in the tri-border region where Brazil, Paraguay and Argentina intersect, Iran is involved in various activities, like drug smuggling and money laundering.

In the main, Brazilian officials, although aware of Iran’s inroads, are complacent about the danger they pose. Even as Brazil understands that Iran uses it as a staging-ground, it does not perceive itself to be a potential target of terrorist activities. Therefore, Brazilian authorities are reluctant to move decisively against signs of Iranian clandestine and criminal activities in their country.

Ultimately, however, Brasilia is going to be forced to take action. Because Brazil is hosting the 2014 FIFA World Cup and the 2016 Olympic Games, homeland security has become a cardinal concern. As a result, the Brazilian parliament is now considering two separate pieces of terrorism-related legislation. If passed, they would strengthen the legal framework governing counterterrorism in Brazil. It would also begin to constrain the ability of bad actors, like Iran and its terrorist proxies, from exploiting the country as part of its growing intrusion into the Americas.

Brazil’s newfound focus on counterterrorism represents an opportunity for the United States, which should try to expand its dialogue with the Rousseff government regarding regional security across Latin and North America. As Ahmadinejad’s visit has made clear, if Washington doesn’t engage Brazil on those fronts, Tehran surely will.

Ilan Berman is vice president of the American Foreign Policy Council in Washington, D.C.