Hundreds of thousands of Brazilian immigrants and their descendants have settled in Paraguay, often buying up land for large-scale agriculture in a country with a much smaller population. Called Brasiguayos, they have been both celebrated for helping Paraguay’s economy boom and demonized for controlling large tracts of land, at times leading land activists to burn Brazilian flags.

More than a century ago, before it became a republic, Brazil was an empire with occasional designs on neighbors’ territory, often serving as an arbiter in disputes in Latin America.

Brazil now relies on a sophisticated diplomatic corps, rising foreign aid payments and the deep pockets of its development bank, which finances projects not just in Latin America but in Africa as well.

Image Brazil is financing projects in several neighboring countries. Credit... The New York Times

“When Kissinger came to Brazil more than three decades ago, he warned his hosts that they could end up being feared rather than loved by their own neighbors,” said Matias Spektor, a professor at Brazil’s Fundação Getulio Vargas, an elite educational institution, referring to the former American secretary of state, Henry A. Kissinger, and his efforts to forge stronger ties with Brazil in the 1970s.

“Now Brazil is engaging Latin America more deeply, without a clear policy of addressing the anxiety that can accompany this process,” Mr. Spektor said. “There’s the real danger of being on the receiving end of anger in certain places.”

Here in Bolivia, the United States once had unrivaled influence, before Mr. Morales’s election in 2005. Since then, Mr. Morales has clashed repeatedly with Washington while warming to other countries, notably Brazil, Venezuela, Cuba and Iran. Since 2008, when Mr. Morales expelled the American envoy, Philip S. Goldberg, the United States has not had even an ambassador here.