Three recent, but apparently unrelated, attacks in the Denver area on newly arrived political refugees from Bhutan have frightened a fragile community. “Before leaving the refugee camp, I was thinking: We have problems. . . . I’ll feel safe in the United States. Now my feeling has changed. I’m not safe in the United States,” said Yadav Rizal, 39, who was robbed of $250, beaten and dragged behind a liquor store in northeast Denver. The attacks aggravate a difficult situation for refugees. The government grants them only $450 a month for eight months to resettle, forcing most to live in rougher areas where police and caseworkers say street crime is more frequent. Those who find work in the anemic economy often ride buses late at night. The Nepali-speaking, Hindu refugees from Bhutan now number about 530 in the Denver area.