The top Republicans on the Senate and House Judiciary Committees are questioning Homeland Security Secretary Janet Napolitano about the release this week of hundreds of illegal immigrants being held in detention centers.

Sen. Chuck Grassley (Iowa) and Rep. Bob Goodlatte (Va.), in a letter to Napolitano, said the “poorly reasoned” decision to transfer the illegal immigrants to a supervised release program was evidence she hadn’t effectively prepared for the automatic sequester cuts set to take effect Friday. The lawmakers charged that Napolitano was violating her department’s main security mission.

“While the administration is clearly embarking on a campaign to scare the public and Congress about the realities of budget reductions, it is clear that you have not planned adequately for the March 1 sequestration,” said Grassley and Goodlatte in the letter dated Feb. 27 and released Thursday morning.