Exhibit 99.1
JOINT FILING AGREEMENT
In accordance with Rule 13d-1(k)(1)(iii) under the Securities Exchange Act of 1934, as amended, the persons named below agree to the joint filing on behalf of each of them of a Statement on Schedule 13D (including amendments thereto) with respect to the Common Stock, par value $0.10 per share, of Aerojet Rocketdyne Holdings, Inc. This Joint Filing Agreement shall be filed as an Exhibit to such Statement.
| Dated: December 26, 2017 | STEEL PARTNERS HOLDINGS L.P. |
| By: | Steel Partners Holdings GP Inc. General Partner |
| By: | /s/ Jack L. Howard | |
| Jack L. Howard, President |
| SPH GROUP LLC |
| By: | Steel Partners Holdings GP Inc. Managing Member |
| By: | /s/ Jack L. Howard | |
| Jack L. Howard, President |
| SPH GROUP HOLDINGS LLC |
| By: | Steel Partners Holdings GP Inc. Manager |
| By: | /s/ Jack L. Howard | |
| Jack L. Howard, President |
| STEEL PARTNERS HOLDINGS GP INC. |
| By: | /s/ Jack L. Howard | |
| Jack L. Howard, President |
| STEEL EXCEL, INC. |
| By: | /s/ Jack L. Howard | |
| Jack L. Howard, President |
| STEEL PARTNERS, LTD. |
| By: | /s/ Jack L. Howard | |
| Jack L. Howard, President |
/s/ Jack L. Howard | |
| JACK L. HOWARD as Attorney-In-Fact for Warren G. Lichtenstein |
