WASHINGTON (AP) – The Pentagon’s acquisition chief said Friday a shipbuilding swap agreed to by Northrop Grumman Corp. and General Dynamics Corp. will benefit both U.S. shipbuilders as they look to preserve jobs, but will come with some hard adjustments.

Defense Secretary Robert Gates’ announced earlier this month that General Dynamics’ Bath Iron Works in Maine would build all three next-generation destroyers, rather than splitting the work with Northrop Grumman Corp.’s Ingalls shipyard in Mississippi.

While all parties have agreed to hash out a mutually agreeable plan, negotiations are still under way.

Under the plan, the Ingalls yard will be in charge of managing the restart of the DDG-51 ship, an older Navy destroyer, that will be slightly less than the previously anticipated workload, according to the Pentagon. The shipyard will now be working on four ship programs, rather than five.

The first Zumwalt – a next generation destroyer – is expected to cost $3.2 billion, but that price tag is likely to rise because of the Navy’s decision to buy only three ships, rather than the seven planned. Eventually, the cost of the newest destroyer will be around $2.5 billion, while the DDG-51 will cost around $2 billion.

The outgoing acquisition czar, John Young, said the working proposal will impose difficult decisions for both companies as they reorder their man-hours, vendors, cash flow and account for any profit changes.

Even so, the swap will ensure both shipyards will have ongoing production for five years, enough time to stabilize the work force, a major concern for lawmakers, Young noted. Over time, it would also be less costly to taxpayers, he added.

Both Northrop Grumman and Bath Iron Works said it was premature to discuss business and financial implications of the proposals with many details still left to be resolved.

Still, Bath Iron Work’s spokesman Jim DeMartini said if Gates’ plan goes through as is, it would provide near-term stability that wouldn’t have been there otherwise. Northrop Grumman’s Jerri Dickseski said the swap would be “very positive” for its business.

Shares of Northrop fell 14 cents to $47.67 in after-hours trading, after shares added 62 cents to close at $47.81. While shares of General Dynamics fell 39 cents to $46.16 in after-hours trading, after shares added $1.01, or 2.2 percent, to close at $46.55.