June 19 (UPI) -- Rwanda will sign a U.S.-Qatar-mediated peace agreement with neighboring Democratic Republic of the Congo, bringing an end to a decades-long armed conflict within days. The two sides' technical delegations initialed the pact Tuesday in Washington, pledging to "disengage and disarm," deal with non-state armed groups, establish a joint security cooperation mechanism and allow refugees and displaced people to return, the State Department said in a statement. Secretary of State Marco Rubio, who has been heavily involved in bringing the deal to fruition, will witness the official signing by ministers from Rwanda and the DRC at a ceremony in Washington on June 27. "The agreement was developed over three days of constructive dialogue regarding political, security, and economic interests. The agreement includes provisions on respect for territorial integrity and a prohibition of hostilities," the State Department said. Its statement paid tribute Qatar's contribution in helping to close the gap between the two countries' individual initiatives aimed at bringing peace to the region. The deal comes two months after Rubio persuaded the parties to sign a peace framework after the violence escalated to unprecedented levels in January as Rwandan-backed M23 rebels overran large areas of northeastern DRC, displacing tens of thousands of people. The region already was reeling from one of the world's worst humanitarian crises when the rebels launched their offensive, overwhelming government forces and killing U.N. peacekeepers, firing on U.N. humanitarian facilities and sending people fleeing from displacement camps. The BBC said that peace in the region could unlock billions of dollars of investment from the West into the resource-rich country, which has vast reserves of many critical minerals, including rare earths. According to the U.S. Commerce Department, DRC has "substantial" untapped deposits of gold, cobalt and high-grade copper, as well as diamonds and lithium, a key element for powering the green power transition. However, that mineral wealth has been disastrous for the country, historically, and is blamed, at least in part, for the current conflict, with DRC officials accusing Kigali of purposefully destabilizing its neighbor to get its hands on the minerals. The DRC reportedly offered access to its resources to the United States in exchange for assistance in resolving the conflict after it effectively lost control of the east of the country at the beginning of the year. In February, the U.S. Treasury Department imposed sanctions on Rwandan Regional Integration Minister James Kabarebe for backing the M23 along with Lawrence Kanyuka, a senior member of the group, and two of his companies. Condemning M23 human rights abuses, including killings, sexual violence and attacks against civilians, Treasury officials said Kabarebe, a former Rwandan Defense Force general, was responsible for RDF coordination with the M23 and was in charge of revenue generation of both outfits, funded from the DRC's mineral resources. The Treasury Department's Office of Foreign Assets Control alleged Kabarebe managed the cross-border movement of minerals taken from mining sites in the DRC, which subsequently found their way onto the international market after being exported from Rwanda.