Ugandan President Yoweri Museveni and President John Magufuli of Tanzania signed the “host and implementation agreement” Sunday in the remote Tanzanian town of Chato.

Construction of the 897-mile pipeline is expected to begin in 2021 and will cost an estimated $3.5 billion, according to Ugandan authorities who expressed optimism that money Uganda will earn from its oil deposits will finance ambitious infrastructure projects and launch the country into middle-income status. No further details about the agreement were released, including who will build the pipeline or how it will be financed.French oil giant Total, a major investor in Uganda’s oil industry, announced last week that it had reached a deal with Ugandan authorities governing the crude oil export pipeline that will cross sensitive protected areas, rivers, and farmland.

“The conditions are set for the ramp-up of project activities and in particular, we will resume the land acquisition activities in Uganda while respecting the highest human rights standards,” Total’s Uganda office said in a statement.

Despite the assurances, local and outside watchdog groups have warned that the rights of local communities are at risk because of the pipeline project, which could displace over 12,000 families and endanger vital ecosystems.