The US Navy’s ultra-versatile new $440 million warship might have to ride out the rest of winter frozen to a dock in Canada. But the sailing branch says it expects to formally accept a new 610-foot-long vessel into service in the coming weeks, its second Zumwalt-class stealth battleship.

The catch? Its main weapons don't have any ammunition. And possibly never will.

The future USS Michael Monsoor, which was nearing completion at Bath Iron Works shipyard in Maine in mid January, is the second in a three-ship class of high-tech vessels with hard-to-detect downward-sloping hulls, a huge flight deck for helicopters and drones, and a sophisticated on-board computer network. Each ship, named after a Navy SEAL who died in Iraq in 2006, costs around $4 billion, not including the $10 billion the Navy spent on research and development for the class, according to the Congressional Research Service. The sailing branch was originally slated to buy as many as 32 of the new ships, but ultimately cut the planned production run to just three owing to the high per-vessel cost.

Arguably the centerpiece of the ships' design is the Advanced Gun System, a unique, 155-millimeter-diameter cannon that can shoot GPS-guided shells as far as 60 miles. Each _Zumwalt_-class ship has two AGSs along with vertical launchers for at least 80 missiles.

The idea was that the _Zumwalt_s would be able to sail close to enemy-held beaches and bombard defenses with smart shells, clearing the way for US Marines to storm ashore.

But as the number of ships in the class shrank, so too did the number of shells the Navy needed to arm them. A Zumwalt can pack up to 600 rounds in its magazine. As production volume contracted, efficiencies dwindled and the per-shell cost rose to nearly $1 million.

In late 2016, the Navy admitted it couldn’t afford to spend $600 million per vessel to arm just three ships with a full ammo load. The service cancelled its planned first batch of 2,000 shells, and also suspended a $250 million effort to modify the AGSs to be compatible with different, cheaper rounds.

Those changes left the fleet's newest and most sophisticated warships without their most important ammunition and sent the Navy scrambling to find new missions for the vessels. After months of deliberation, in early January the Navy announced the Zumwalts would switch from bombarding beaches to hunting other ships. A Zumwalt "will serve as a focused surface-strike asset that can be deployed with existing long-range weapons," Lt. Lauren Chatmas, a Navy spokesperson, told me.

There's just one problem with that plan. The Navy doesn't have enough replacement anti-ship missiles for the _Zumwalt_s' launchers. And likely won't for many years.

For decades the Navy faced no major rival on the open ocean. As a consequence, it allowed its missile arsenal to shrink and grow obsolete, even as Russia and China developed better and better ship-destroying missiles.

The farthest-flying Russian anti-ship missile today can hit US ships from as far as 300 miles away. The current longest-range American missile, the 1970s-vintage Harpoon, can travel just 125 miles. "Surface combatants today cannot engage submarines, surface ships or aircraft from outside enemy anti-ship missile range," Bryan Clark, an analyst with the Washington, DC-based Center for Strategic and Budgetary Assessments, warned in a 2014 study.

In late 2107 the Navy finally began buying new, longer-range anti-ship missiles capable of flying at least 200 miles. But the new Long-Range Anti-Ship Missile, as it’s known, is expensive. The Navy bought just 23 of the missiles in 2017 for a total cost of nearly $90 million. Loading all of a Zumwalt's 80 missile launchers with the new munition could cost $300 million.

Granted, that's less than the price of a full load of smart shells. But the missiles' high cost limits how fast the fleet can acquire them. It could be years before there are enough munitions in the arsenal to arm all three _Zumwalt_s, to say nothing of equipping the Navy's roughly 80 other destroyers and cruisers.

Analysts say they're optimistic that, with new weapons and other upgrades, eventually the Zumwalt class will be effective. "A large and powerful warship like the Zumwalt was built from the ground up to be flexible and adaptable," Eric Wertheim, an independent naval expert and author of Combat Fleets of the World, told me.

A key part of that will be not attempting to tailor a new system into old plans, according to Peter W. Singer, a military analyst with the New America Foundation. “And also being willing to explore mounting new systems on it," Singer said.

To that end, the Navy told me it will soon announce plans to modify the _Zumwalt_s to be better destroyers of ships. The changes, which could include new sensors and additional new missile types, are part of the Navy's budget proposal for 2019.

One thing is certain. For several years at least, the Navy's newest warships will lack a full load of weapons for the missions the fleet expects them to perform.