Studies are underway to “take a hard look” at putting eight mothballed Oliver Hazard Perry frigates back into service as well as extending the life of existing Arleigh Burke guided-missile destroyers to help the Navy reach its goal of a 355-ship fleet, Chief of Naval Operations Adm. John Richardson said on Tuesday.

Speaking before an audience at the U.S. Naval War College, Richardson said service leaders were looking at “every trick” to put more platforms into the fleet including bringing back some Perrys into service.

“We’re taking a hard look at the Oliver Hazard Perry-class frigates. There’s seven or eight of those that we could take a look at but those are some old ships and everything on these ships is old… a lot has changed since we last modernized those,” Richardson said in a response to an audience question on how the Navy’s inactive reserve fleet could be used to grow the fleet.

“It’ll be a cost benefit analysis in terms of how we do that. The other part is how we do life extension and how do we plan to keep them out of mothballs longer. That’s going to be money in the bank if we do that.”

He said early looks at extending the planned service life of the Arleigh Burke-class guided-missile destroyers could help the service reach a 355 total ten to 15 years faster.

“If we plan now, for instance, to extend the life Arleigh Burke DDGs beyond the current projections, the initial returns are we could buy ten to 15 years to the left in terms of reaching that 350 ship goal,” he said.

In follow-up tweets to his remarks at the Current Strategy Forum, Richardson and a Navy spokesperson stressed the service was still in the early stages of formulating how it would reach the 355 ship goal and that the progress on the life extension program was more mature than reactivating the frigates.

The service – currently at 275 ships – determined late last year that it needed to grow to 355 ships by the mid-2020s to keep a U.S. advantage over adversaries like Russia and China.

“It’s clear to get beyond that we’re going to have to start building, we’re going to have to build ships,” Richardson wrote in a white paper issued last month.

“And we’re going to have to look at extending the life of ships, we’re going to have to look at just about every way we can to increase our inventory of ships in the United States Navy.”

One naval analyst told USNI News on Tuesday considering reactivating the frigates was a sign of the stress the current fleet is under.

“The fact that this is being considered speaks to the strength and utility of the Perry-class frigate design, as well as the strain being felt by the fleet,” Eric Wertheim, author of U.S. Naval Institute’s Combat Fleets of the World, told USNI News on Tuesday.

“While increasing maintenance and shipbuilding funding could help alleviate some of these challenges in the future, near term gaps still need to be addressed more immediately. Returning retired vessels to the fleet could potentially be one near-term solution, and it sounds like it is now being considered – among other options.”

Bryan Clark, a naval analyst at the Center for Strategic and Budgetary Assessments and former aide to retired former Chief of Naval Operations Adm. Jonathan Greenert, told USNI News that the missions for the frigates would be limited and the cost would be high in reintroducing them to the fleet.

“The Perry class are going to be an expensive proposition to bring out of mothballs and maintain just for the purpose of going out and doing some presence missions,” Clark said.

“You’re talking about having to come up with a 150 billets for each of those ships out of an already stressed manpower pool. They’re also not going to offer that much in terms of combat capability. So if you bring them back, they’re essentially going to be like how they were when they left the fleet, which was as a theater security cooperation, maritime security asset.”

The last Perry left U.S. service in 2015 with the bulk of the class set aside for foreign military sale or dismantling.

Originally designed as a guided missile frigate, the class was a key platform for the U.S. during the Iran-Iraq War in the late 1980s and later was a key platform for anti-drug trafficking operations in U.S. Southern Command.