France and Germany are progressing their plans to develop a next-generation combat aircraft and will launch demonstrator programmes for the aircraft and engine in mid-2019.
Announcing the move on Twitter, French defence minister Florence Parly said the partners have taken a "decisive step" to build on June's decision to pursue the joint effort.
She says the new pact will see the start of studies covering the proposed design and architecture, as well as the launch of demonstrators for the aircraft and engine by mid-2019.
France's Dassault is leading the effort, with Airbus Defence & Space representing the German side.
In addition, propulsion specialists MTU Aero Engines and Safran are in talks to collaborate on the development of the type's powerplant.
MTU says it cannot give details on the structure of any pact with the French firm but describes it a "natural partnership".
"We are working ahead on that topic together with Safran," it adds. The two companies have previously worked together on military engines, including as key members of the Europrop International consortium producing the TP400 for the A400M Atlas tactical airlifter.
The future combat aircraft programme seeks to replace France and Germany's respective fleets of Dassault Rafales and Eurofighter Typhoons from 2040.