Speaking to a conference of defense ministers from the Americas, where militaries are often used to battle drug traffickers and other guerrilla groups, Panetta said the U.S. realizes that it's sometimes difficult to decide if a threat requires the use of the military or law enforcement.
"In some cases, countries have turned to their defense forces to support civilian authorities," Panetta said in remarks prepared for delivery. "To be clear, the use of the military to perform civil law enforcement cannot be a long-term solution."
Panetta's comments were aimed at a number of Latin American countries who turn to their militaries to fight crime or help restore order, particularly for counterdrug operations or other instances to quell violent criminal cartels. But countries here have also, at times, been critical of the U.S. for what they see as a similar blurring of the enforcement lines by America—particularly the detention center at the U.S. base in Guantanamo, Cuba, where suspected terrorists have been held since not long after the Afghanistan war began.
The U.S., he said can help countries ensure that they improve their abilities while still respecting human rights, laws and civilian authorities.
"We can and we will provide a helping hand, but ultimately civilian authorities must be able to shoulder this burden on their own," he said.
In his remarks during the opening session of the 10th Conference of Ministers of Defense of the Americas, Panetta also encouraged the ministers to approve a new plan to set up a database that will allow the nations to better coordinate their responses to disasters.
This is Panetta's second trip to South America this year, as he works to expand U.S military cooperation in the region and build on relationships that also can help shore up America's interests in the Asia-Pacific region. He stopped in Peru for meetings with leaders there before traveling to Uruguay.
The database would be at the core of a new system that will help nations organize humanitarian relief efforts in the event of a disaster. The database would allow countries to list the types of aid they are ready to provide and allow the affected nation to choose, in order to avoid duplication and better meet urgent needs.
Officials have said that while there was a lot of assistance sent to Haiti, it wasn't well coordinated and there was a lot of duplication. Defense officials are hoping that the database would solve some of those problems.
"Western Hemisphere nations worked together to provide much-needed help, but we lacked a mechanism to collaborate in real-time and focus our efforts where they were needed most," said Panetta about the Haiti disaster response. Implementing the new system, he said, will help nations be ready to respond quickly when the next disaster strikes.
In his visit to Colombia, Brazil and Chile earlier this year, Panetta underscored Latin America's importance as military partners in the Pacific, where China is challenging U.S. influence in a number of countries. As those defense relationships grow, officials say it can only help U.S. economic and political ties across South America.
Panetta emphasized again Monday that the U.S. does not want to establish permanent bases in the region or take on any dominant role of defending other countries on the continent.
"Our goal is to work with those nations that want us to help them to develop their capabilities so that they can defend and secure themselves. Our interest is to work with you, not against you," he said.