Defense Secretary Donald H. Rumsfeld (search) wants Western Hemisphere countries to cooperate with one another to stem "anti-social, destabilizing behavior" like corruption, gangs and drug trafficking.

"The kinds of problems that the hemisphere faces are problems that don't lend themselves to single-nation solutions," the Pentagon chief said while embarking on a three-day Latin American trip.

Rumsfeld's frequent visits to the region — it's his third such trip in 10 months — come amid concerns about what U.S. officials call stepped-up efforts by Cuba and Venezuela to install more leftist governments in Latin America by targeting volatile countries like Bolivia.

In Paraguay's capital city, Rumsfeld met with President Nicanor Duarte Frutos (search) and was meeting with Minister of Defense Roberto Gonzalez Segovia, in part, to gauge their views on the escalating involvement of Cuban President Fidel Castro (search) and Venezuelan President Hugo Chavez (search) in the region.

"There are countries like Paraguay and others, their neighboring countries, they're all interested in being able to grow and function in a manner that's free of external influence and to do things in ways that fit their history and their circumstance," Rumsfeld said Tuesday.

A country considered friendly with the United States and wary of Castro and Chavez, Paraguay shares its northwestern border with Bolivia. That country has been headed by an interim president since the June ouster of President Carlos Mesa and his U.S.-backed government after just 19 months in power.

In June, President Bush urged the nations of the Western Hemisphere to work together to prevent governments in the region from backsliding to authoritarian rule. Bush didn't name aggressors that may be present such a threat, but a Venezuelan official said the U.S. seemed to be aiming at his country.

Since then, U.S. officials and Chavez, who counts Castro as a mentor, have engaged in an escalating war of words over whether the two leaders are supporting opposition movements in Bolivia and elsewhere.

"There certainly is evidence that both Cuba and Venezuela have been involved in the situation in Bolivia in unhelpful ways," Rumsfeld told reporters Tuesday while traveling to Latin America.

Rumsfeld would not elaborate on his assertion, but U.S officials, including one of Rumsfeld's own deputies, have said that Cuba has provided organizational support and Venezuela has provided financial resources to Evo Morales, a Bolivian presidential hopeful.

Morales is a populist who leads Bolivia's coca growers and was a key player in the massive protests that led to Mesa's downfall.

Chavez denies trying to destabilize Bolivia and other countries by backing what one U.S. official has called antidemocratic groups. In turn, Chavez has accused the United States of spreading lies to try to isolate his government.

In the year since the Venezuelan president survived a presidential recall referendum, the U.S. strategy has been to avoid provoking him.

But defense officials say that strategy is changing given that Chavez is emerging as a strategic leader and Cuba has reasserted its influence in the region.

Chavez has spent the past year courting a growing group of moderate leftist presidents in Latin America by urging more unity among countries in the region and less with the United States.

Defense officials say the United States can't respond to the Cuba-Venezuela partnership alone and needs help from the region.