Assembly for an aircraft having a wing and an engine pylon for mounting a jet engine beneath said wing , the engine pylon having: - a primary structure forming a box and having a starboard-side lateral panel , a port-side lateral panel , an upper spar , a lower spar and a rear rib that closes the box at the rear, - a first and a second set of upper shackles , wherein the first set of upper shackles fastens, in use, the starboard-side lateral panel to a structural element of the wing , and wherein the second set of upper shackles fastens, in use, the port-side lateral panel to a structural element of the wing , - a first and a second set of lower shackles , wherein the first set of lower shackles fastens, in use, the starboard-side lateral panel to a structural element of the wing , and wherein the second set of lower shackles fastens, in use, the port-side lateral panel to a structural element of the wing , - a fastening element secured to either the rear rib or the lower spar , - a rear rod that connects the fastening element to a structural element of the wing , and - a transverse shackle that connects the upper spar to a structural element of the wing , wherein the line connecting the two centres of the transverse shackle is oriented transversely with respect to a longitudinal axis of the engine pylon , - a reinforcing panel (280a-d), at each join between a starboard-side or port-side lateral panel (208a-b) and a shackle of the first or second set of upper or lower shackles , which is fastened along the height against the starboard-side or port-side lateral panel (208a-b) and to which said shackle of the first or second set of upper or lower shackles is also fastened. - a primary structure forming a box and having a starboard-side lateral panel , a port-side lateral panel , an upper spar , a lower spar and a rear rib that closes the box at the rear, - a first and a second set of upper shackles , wherein the first set of upper shackles fastens, in use, the starboard-side lateral panel to a structural element of the wing , and wherein the second set of upper shackles fastens, in use, the port-side lateral panel to a structural element of the wing , - a first and a second set of lower shackles , wherein the first set of lower shackles fastens, in use, the starboard-side lateral panel to a structural element of the wing , and wherein the second set of lower shackles fastens, in use, the port-side lateral panel to a structural element of the wing , - a fastening element secured to either the rear rib or the lower spar , - a rear rod that connects the fastening element to a structural element of the wing , and - a transverse shackle that connects the upper spar to a structural element of the wing , wherein the line connecting the two centres of the transverse shackle is oriented transversely with respect to a longitudinal axis of the engine pylon , - a reinforcing panel (280a-d), at each join between a starboard-side or port-side lateral panel (208a-b) and a shackle of the first or second set of upper or lower shackles , which is fastened along the height against the starboard-side or port-side lateral panel (208a-b) and to which said shackle of the first or second set of upper or lower shackles is also fastened. <EOS>