The Coast Guard's proposed FY2018 budget requests $19 million in acquisition funding for a new polar icebreaker that the Coast Guard wants to begin building in FY2019. The total acquisition cost of a new polar icebreaker had generally been estimated informally at roughly $1 billion, including design costs, but a congressionally mandated July 2017 report from the National Academies of Sciences, Engineering, and Medicine (NASEM) on the acquisition and operation of polar icebreakers estimates that the ship could cost less (and perhaps considerably less) than $1 billion. The project to acquire a new polar icebreaker was initiated in the Coast Guard's FY2013 budget submission. The project has received about $220.6 million in acquisition funding through FY2017, including $175 million in FY2017 that was provided in the Coast Guard's acquisition account ($25 million) and the Navy's shipbuilding account ($150 million). The operational U.S. polar icebreaking fleet currently consists of one heavy polar icebreaker, Polar Star, and one medium polar icebreaker, Healy. In addition to Polar Star, the Coast Guard has a second heavy polar icebreaker, Polar Sea. This ship suffered an engine casualty in June 2010 and has been non-operational since then. Polar Star and Polar Sea entered service in 1976 and 1978, respectively, and are now well beyond their originally intended 30-year service lives. Coast Guard polar icebreakers perform a variety of missions supporting U.S. interests in polar regions. A Department of Homeland Security (DHS) Mission Need Statement (MNS) approved in June 2013 states that "current requirements and future projections ... indicate the Coast Guard will need to expand its icebreaking capacity, potentially requiring a fleet of up to six icebreakers (3 heavy and 3 medium) to adequately meet mission demands in the high latitudes...." The current condition of the U.S. polar icebreaker fleet, the DHS MNS, and concerns among some observers about whether the United States is adequately investing in capabilities to carry out its responsibilities and defend its interests in the Arctic, have focused policymaker attention on the question of whether and when to acquire one or more new heavy polar icebreakers as replacements for Polar Star and Polar Sea. On October 26, 2016, the Coast Guard released a request for information (RFI) to receive industry feedback on its notional polar icebreaker acquisition approach and schedule. The summary of the RFI, dated October 25, 2016, presents a notional schedule for acquiring three heavy polar icebreakers under which procurement of long leadtime materials (LLTM) for the three ships would start in the fourth quarter of FY2019, the second quarter of FY2021, and the second quarter of FY2022, respectively, and the ships would be delivered in the fourth quarter of FY2023, the second quarter of FY2025, and the second quarter of FY2026, respectively. The summary of the RFI states that the Coast Guard currently envisions having a single U.S. shipyard build all three ships under a contract with options. A contract with options can be viewed as a form of annual contracting. An alternative would be a block buy contract. A block buy contract would reduce the government's flexibility regarding whether and when to acquire the second and third ships, and what design to build them to, and in return reduce the combined acquisition cost of the three ships. CRS estimates that compared to costs using a contract with options, using a block buy contract that included batch purchases of materials and components for the three ships would reduce the combined acquisition cost of the three ships by upwards of 7%, which could equate to a savings of upwards of $200 million. The July 2017 NASEM report recommends using a block buy contract to procure a single class of four science-ready heavy polar icebreakers to meet (along with continued operation of Healy) U.S. needs for both heavy and medium polar icebreakers.