BATH — The Navy has submitted a request for proposals for more destroyers to be built by either Maine’s Bath Iron Works or Mississippi’s Ingalls shipyard, or both.

The Naval Sea Systems Command issued its final request Thursday for Arleigh Burke-class destroyers built with ballistic missile defense capability.

The contract covers the fiscal years 2018 through 2022.

The request for proposals doesn’t mention the number of ship, but earlier Navy documents envisioned up to 10 destroyers, with options for more.

BIW said Friday that the company will be assessing the latest request but had no further comment.

BIW, which employs roughly 5,500 people, was awarded a contract last fall to build two Arleigh Burke-class destroyers. The Arleigh Burke is a multi-mission ship that offers defense against a wide range of threats. At that time, there were four destroyers under various stages of construction.

There are also two Zumwalt-class, or stealth destroyers, in production at BIW and one more planned by the end of this decade. There has been concern, however, that the amount of work at the Bath shipyard could drop off when the Navy takes delivery of the third and final Zumwalt-class destroyer sometime later this decade.

Maine lawmakers are currently debating a bill that would extend a 20-year-old tax credit program that could be worth tens of millions of dollars for BIW. The Shipbuilders Tax Credit was created specifically to encourage the shipyard to make significant hires and investments. To be eligible, a shipbuilding facility would have to spend at least $100 million after January 2018 on construction, modernization or expansion. The legislation as proposed would allow a shipbuilding facility an annual income tax credit worth 3 percent of its investment.

The shipyard also has sought recently to turn the page on a difficult chapter in labor relations.

Dirk Lesko, BIW’s new president, has been trying to rebuild trust lost by his predecessor, Fred Harris, who angered many of the shipyard’s workers by removing a blue “BIW” flag, a shipyard symbol for years, and insulted them by declining to use the oft-repeated phrase “Bath-built is best built.” He also sought to have lower-wage contractors do more work on ships.

Many felt Harris was an outsider who won deep concessions from unionized workers to compete for a lucrative Coast Guard contract, only to see it awarded to a competitor.