Lockheed Martin The US Navy can't fire its awesome new gun that can hit a target more than 70 miles away because the rounds are costing the service nearly a million bucks a piece.

Just a couple weeks after the Navy commissioned its most advanced warship, the USS Zumwalt (DDG-1000), the service says it won't be buying any more of the guided precision munitions the ship's Advanced Gun Systems uses, called the Long Range Land-Attack Projectile (LRLAP).

The 155mm round is "the most accurate and longest-range guided projectile" in Navy history, according to Lockheed Martin. It's also one of the most expensive, with the price of each round costing roughly $800,000 to $1 million, for a total cost of around $2 billion if the service purchased its planned buy of 2,000 rounds, Sam LaGrone of USNI reported.

The Navy wasn't expecting the exorbitant cost when it first began producing the advanced Zumwalt-class destroyers.

It originally planned to build 32 of the stealth ships, but cost overruns led the service to eventually reduce the number down to just three. That reduction in the number of ships also led the cost of its ammunition to rise, Defense News reported.

“We were going to buy thousands of these rounds,” a Navy official familiar with the program told the site. “But quantities of ships killed the affordable round.”

The Navy is now looking for alternative rounds that can be fired out of the AGS system, though its possible a replacement will not be found by the time the Zumwalt finishes sea trials and is integrated into the fleet by 2018. The service is looking at a number of alternative rounds, though a replacement could be tricky since the gun was built specifically for the LRLAP round.

The rounds aren't the only budget-busting item, however. The three Zumwalt-class ships themselves — the newly-commissioned USS Zumwalt, and not-yet-commissioned Michael Monsoor and Lyndon B. Johnson — cost about $4 billion each.

Navy spokesperson Capt. Thurraya S. Kent provided the following statement to Business Insider:

"The Navy continuously monitors the gun and ammunition industry capability and capacities. To address evolving threats and mission requirements, the Navy has evaluated industry projectile solutions — including conventional and hyper-velocity projectiles — that can also meet the DDG 1000 deployment schedule and that could potentially be used as an alternative to LRLAP for DDG 1000."

This post was updated on 11/8/2016 at 9:25 a.m. with a statement from the US Navy.