This report provides background information and issues for Congress on the sustainment and modernization of the Coast Guard's polar icebreaker fleet, which performs a variety of missions supporting U.S. interests in polar regions. The Coast Guard's proposed FY2015 budget requests $6 million to continue initial acquisition activities for a new polar icebreaker. The issue for Congress is whether to approve, reject, or modify Coast Guard plans for sustaining and modernizing its polar icebreaking fleet. Congressional decisions on this issue could affect Coast Guard funding requirements, the Coast Guard's ability to perform its polar missions, and the U.S. shipbuilding industrial base.