In September 2011, Argentina, Venezuela and Bolivia initiated jointly military operations, against Brazil and Uruguay, in three different fronts. This scenario covers the region known as "Acre", in southern Brazilian Amazonia. It is the Acre War or "Guerra do Acre".

After the Cold War the South American Nations, were, most of them, weak politician governments, based upon populism, demagogy and corruption.

Bolivia: After 4 years of economical and political crisis, the reelection of the president was obtained with the promise of a "National Goal": to conquest back the territory of the Acre in southern Brazilian Amazonian region with military assistance of Venezuela and training from Argentina and Cuba.

Venezuela: The "XXI Century Socialism" politics established a Dictatorship supported by the increasing international oil price. Externally, Venezuela assumed Cuba's political orientation. Militarily, the Armed Forces began in 2003 a reinforcement program re-equipping with T-72 tanks, AK assault rifles, Sukhoi fighters, Mi helicopters and Namur submarines. In 2010, Venezuelan forces occupied the litigated Guiana Republic western area. The UN Security Council complained, but no action was taken, giving the "Bolivarian Army" a successful baptism of fire and the confidence in his ability to bend the rest of South America.

Brazil: In 2010, the government has lost the rest of its people credits due to the Presidential involvement with corruption. Public Health, Education, Social Security systems are disorganized and bankrupted. The government attempt of changing the Constitution to establish a dictatorship like Venezuela was stopped by the population going to the streets against it. The President paramilitary arm tries to keep people under control thru terrorism, urban violence, strikes, and chaos.
Traditionally the Brazilian Army's troops come from people conscription and the officers, mostly, come from middle classes, so it is a picture of the Nation and always reflected that by having the day-by-day people respect and confidence. The Brazilian Army, "Strong Arm, Friendly Hand", is considered "the most reliable institution".

As soon as the result of the October 2010 Brazilian Presidential Election was announced with a completely revamped government and congress, many of the former government people, including the president, negotiated an agreement where in change to go back and establish in Brazil a pastiche government, each country would get:
Venezuela: Northern Amazonian area (Roraima);
Argentina: Uruguay and Southern Brazilian area (Rio Grande do Sul);
Bolivia: Southern Amazonian area (Acre);
Paraguay: Itaipu Hydroelectric Power Plant and vicinity.
The Brazilian conspirators and the countries representatives sealed a Pact. The preparative initiated in January 2011: jointly maneuvers, troop's deployment, weapons supplying from the Venezuela's depots. Brazil and Uruguay soon realized what was going on and slowly also began their mobilization.

The main objective for the Bolivian/Venezuelan forces is to quickly conquest Rio Branco (Brazil), as due to the small amount of available reserves there will be a few reinforcements during the period, mostly Venezuelan forces, asking for UN to intervene and going to negotiations after the an unilateral cease fire.
For the Brazilian forces the main objective is to slow down the initial attacks till the reinforcements will begin to arrive from internal mobilization. The secondary objectives would be to invade Bolivian eastern region to force Bolivia to reconsider and ceases fire and/or capitulates.
UN will intervene and there is a possibility of to be established a Cease Fire.