In Farewell to Manzanar, what does Papa burn and why?

Farewell to Manzanar is a memoir written by Jeanne Wakatsuki Houston and James D. Houston. This memoir follows the life of Jeanne, a child of a Japanese immigrant (known as a Nisei), who was born in America. She was seven years old and living in California in 1941, when the bombing of Pearl Harbor by the Japanese took place. Now, because of the tension between the United States and Japan, most Japanese people were afraid of being arrested for simply being on American soil, which is why her father decided to burn his Japanese flag and his identity papers. He was hoping to be able to save himself from being arrested, but he did it in vain; he was still arrested by the FBI and beaten as he was taken to jail.
The next year, in 1942, President Roosevelt signed Executive Order 9066, which stated that anyone who potentially posed a threat to national security could be relocated by the military. This was when Jeanne and her family were taken to the Manzanar Relocation Center, where they suffered inhumane conditions (not enough warm clothes, not enough room for all of them, spoiled food, etc.) alongside many other Japanese Americans. Her family was reunited with her father in this camp, although Jeanne was the only one to be happy with their reconciliation.