Washington state’s two senators have joined six of their senate colleagues in penning a letter to Secretary of Defense James Mattis that calls for Navy shipyard civilian employees to be exempt from the recent presidential memorandum signed by President Trump that freezes federal hiring.

According to the office of U.S. Senator Maria Cantwell, the impact of the hiring freeze could be “particularly harsh” for Puget Sound Naval Shipyard in Bremerton because of the size of the workforce, the number of vacancies at the shipyard, and the importance of the PSNS to Washington state’s $30 billion dollar maritime economy.

While the president’s memorandum says it does not apply to military personnel or positions considered essential to meet national security responsibilities, the uncertainty has caused shipyards across the country to suspend all hiring, Cantwell’s office said.

Also signing the letter Thursday was U.S. Senators Patty Murray (D-WA), Jeanne Shaheen (D-NH), Susan Collins (R-ME), Brian Schatz (D-HI), Mazie Hirono (D-HI), Angus King (I-ME) and Maggie Hassan (D-NH).

“We believe a hiring freeze may have a severe and adverse impact on the ability of the Navy and public shipyards to meet critical national security requirements and we urge you to immediately exempt all Department of Navy shipyard civilian employees,” the senators wrote. “The civilian men and women who support the Navy provide mission critical maintenance to ensure the Navy can meet security requirements around the world, and should thus be granted an exception.

“As you are aware, there is discussion regarding the requirements for a larger Navy to meet current and emerging threats,” the letter continues. “In order to maintain the current fleet and meet future maintenance requirements, we will need more civilians to maintain, repair and overhaul submarines, aircraft carriers and the entire naval fleet. These civilians frequently complete maintenance availabilities ahead of schedule and under budget saving taxpayer dollars and ensuring fleet readiness… A civilian hiring freeze at naval shipyards will severely impact this training pipeline resulting in maintenance delays and higher costs. The Presidential Memorandum states that the freeze is not intended to impact national security, however, freezing the hiring of civilian employees who will support critical fleet maintenance will directly undermine national security.

“We urge you to consider the impact of the Memorandum on the Navy, public shipyards and national security and issue clear guidance to immediately exempt all Navy shipyard civilians from the hiring freeze,” the letter concludes.