WASHINGTON — The White House issued a new call Tuesday to replace the US Coast Guard's tiny two-ship icebreaker fleet, proposing to move the planned 2022 acquisition of one ship to 2020. The administration, in a fact sheet released on the White House web site, also supports "additional icebreakers," although no number was cited.

The proposal is the latest in a long series of nebulous, the-Russians-have-more-so-we-need-more calls from US officials for ships that still have no defined purpose. The White House said the heavy icebreakers are needed to "ensure that the United States can meet our national interests, protect and manage our natural resources, and strengthen our international, state, local, and tribal relationships." But that's a long way from saying exactly how the ships would manage those goals.

The Coast Guard is in the early stages of a new heavy polar icebreaker acquisition program. According to the service's web site, the work includes developing a formal mission need statement, a concept of operations, and an operational requirements document. Adm. Paul Zukunft, commandant of the Coast Guard, said earlier this year the service needs three heavy and three medium icebreakers to cover the polar regions, but noted there was no clear path to creating the ships. There has been no government commitment to a six-ship icebreaker fleet.

The Department of Homeland Security, parent organization of the Coast Guard, has not signed off on how the single ship would be paid for. The Coast Guard said a "whole-of-government" approach is necessary, implying that funding would be needed from other agencies. Congress routinely asks US Navy officials what they're doing about buying an icebreaker, but the Navy replies — rightly — it's a Coast Guard mission.

Obama leaves open the question of funding, calling on Congress only "to work with the administration to provide sufficient resources to fund these critical investments." The Hill also refrains from proposing specific funding sources.

The president, on a trip to Alaska, did not mention the issue Tuesday in his remarks to the GLACIER Conference on Global Leadership in the Arctic: Cooperation, Innovation, Engagement and Resilience. It's not clear what changes he could make in the program to ensure its future before he leaves office in January 2017.

Even if a competition to find a suitable design and builder is completed and the ship is funded in 2020, it would likely be at least five years before a new icebreaker would be in service, meaning a decade from today at the soonest.

It is not clear what role a US icebreaker would play in the expanding use of the Arctic, which will see increasing commercial traffic as the polar icecap continues to melt and navigation channels open up. Those roles need to be defined — not just in the face of dramatically heightened Russian activity at the top of the world, but also to reassure Canada that improving US capability in the region would not threaten their territorial integrity.

Some lawmakers routinely ask those questions of Navy and Coast Guard leaders. But those questions are not for service chiefs to decide. It's up to Congress and the president to define exactly what the new ships would be used for before proceeding much further.