The US Navy is set to decommission amphibious assault ship USS Bonhomme Richard after it was severely damaged in July by what police suspect to have been arson, Navy officials said Monday in an audio-only press conference, ABC News reported.The fire ravaged the ship for five days while it was docked in San Diego at the end of a two year-long $250 million upgrade, at times reaching temperatures of 1,200 degrees Fahrenheit. After taking hundreds of firefighters to combat the blaze, the damage was found was so severe that repairing the 22-year-old ship was simply impractical. According to Navy Regional Maintenance Center commander Rear Admiral Eric H. Ver Hage, the Navy had also considered reconfiguring the USS Bonhomme Richard into a hospital ship. However, like repairing it, this was far too expensive, with estimates placing renovation costs at around $3 billion. For reference, adjusting for inflation, the USS Bonhomme Richard cost the Navy $1.2b., ABC News reported.It is unclear if there are plans to purchase a new ship.“Although it saddens me that it is not cost-effective to bring her back,” Secretary of the Navy Kenneth J. Braithwaite said in a statement, according to local NBC-affiliate in San Diego, “I know this ship’s legacy will continue to live on through the brave men and women who fought so hard to save her as well as the sailors and Marines who served aboard her during her 22-year history.”The decommissioning process will see the usable remnants of the ship scrapped, a process estimated to take nine months to a year and cost around $30 million. The decision followed doubts voiced at the time of the fire by chief of naval operations Admiral Mike Gilday, who was unsure if it would be cost-efficient to repair the ship."I am 100% confident that our defense industry can put this ship back to sea," he said at the time. "But, having said that, the question is: Should we make that investment in a 22-year-old ship? And I'm not going to make any predictions until we take a look at all the facts, and we follow the facts, and we can make reasonable recommendations up the chain of command on the future steps, any repair efforts, future repair efforts of Bonhomme Richard."The fire is one of the worst to ever ravage a US warship outside of combat, and resulted in severe damage to the interior and exterior. According to Ver Hage, repairing it would mean replacing 60% of the entire ship.The exact cause behind the fire remains unclear, but there is heavy suspicion that it was the result of arson. After the fire was put out, the Navy confirmed that a thorough investigation was underway, conducted by the Naval Criminal Investigative Service (NCIS) and the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF), NBC News reported. In August, a Defense Department source with knowledge of the investigation told NBC that a US Navy sailor was identified as a possible suspect.Speaking to NBC on Monday, NCIS confirmed that the investigation remains ongoing.