Brazil and Uruguay have signed cooperation agreements on defence, science, technology, energy, river transportation and fishing, with the hope of accelerating political and economic integration between these two neighbouring countries. Uruguay has two uncontested boundary disputes with Brazil, over Isla Brasilera and the  Invernada River region near Masoller. The two countries disagree on which tributary represents the legitimate source of the Quaraí/Cuareim River, which would define the border in the latter disputed section, according to the 1851 border treaty between the two countries. However, these border disputes have not prevented both countries from having friendly diplomatic relations and strong economic ties. So far, the disputed areas remain ''de facto'' under Brazilian control, with little to no actual effort by Uruguay to assert its claims.