The CIA plans to begin calling thousands of furloughed employees back to work Wednesday, U.S. officials said, in an effort to contain the cumulative toll of a government shutdown stretching into its second week.

In a statement issued Tuesday to the CIA’s workforce, Director John Brennan cited concern about the “potential adverse cumulative and unseen impact on our national security” of furloughs that had forced employees across almost every category of the agency’s workforce to leave their jobs.

U.S. officials said that other intelligence agencies were taking similar steps but declined to disclose specifics on how many or which categories of employees would be summoned back to their jobs, citing the classified nature of their work.

Shawn Turner, a spokesman for Director of National Intelligence James R. Clapper Jr., said Clapper had authorized the recall of “some employees” at the National Counterterrorism Center, the National Counterproliferation Center, the Office of the National Counterintelligence Executive and the National Intelligence Council.

The recalls should ease the impact of the shutdown across the nation’s security apparatus. On Monday, Defense Secretary Chuck Hagel began ordering nearly all of the Pentagon’s 350,000 furloughed civilian workers back to their jobs, citing a reinterpretation of a budget law.

Officials said it would take days to determine how many employees would be recalled, and that more would likely be ordered back to their jobs if the budget stalemate continues.

The move by the nation’s spy chiefs comes after senior lawmakers expressed dismay, and some criticism, at how many intelligence employees were being considered nonessential under federally issued guidelines.

On Friday, Sen. Charles E. Grassley (R-Iowa) sent a letter to Clapper accusing him of “a failure of leadership” for failing to protect more employees at U.S. spy agencies from the impact of the shutdown.

In a hearing last week, Clapper testified that the furloughs were having an “insidious” effect on intelligence gathering and analysis, making the nation more vulnerable to terrorist attacks and other threats.

Alarmed by that assessment, Grassley told Clapper that the decision to furlough so many workers meant that “you either need better lawyers or to make big changes in your workforce.”

U.S. officials insisted Tuesday that the decision to recall thousands of intelligence employees should not be interpreted as an indication that too many had been initially furloughed.

Instead, officials cited a widespread expectation that the shutdown would only last a few days, and said that it began to have a greater impact on critical functions as the budget impasse dragged on.

Brennan said the recall would affect only employees “directly involved in our core missions,” and warned that “there are still important functions that we will not be able to perform.” A CIA spokesman would not elaborate.

Officials had previously said that the cuts affected employees across all branches of the CIA, including analysts as well as employees of the agency’s clandestine service, which is responsible for carrying out spying missions overseas.