The U.S. Navy, in a memo dated March 16 (full text), became the third branch of the armed forces to liberalize its policy on accommodation of religious headgear. As reported by Navy Times:
Previously, religious head coverings like Muslim hijabs and Jewish kippahs were allowed because they did not interfere with uniform covers, but per the March 16 instruction from the Bureau of Navy Personnel, there is no longer a requirement that an approved religious head covering be worn underneath the cover prescribed by the uniform of the day.
[Thanks to Scott Mange for the lead.]