WASHINGTON - Lawyers representing Guantanamo prisoners wrote an open letter to US Defense Secretary Chuck Hagel on Thursday to highlight the “mass hunger strike” at the facility. Forty-five lawyers wrote to Hagel to warn of the “serious threat to the health and life of detainees” who are on hunger strike at the widely reviled jail set up in Cuba after the September 11, 2001 attacks.The letter said Guantanamo’s commander had failed to respond to a request for information about the hunger strike sent on March 4. The lawyers noted that as a Republican senator, Hagel had in 2005 warned that Guantanamo’s existence meant the United States was “losing the image war around the world.”