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