Secretary of State Rex Tillerson is pushing back against the White House’s proposal to drastically slash funding for diplomacy and development, a sign he intends to fight for his department’s mission inside the Trump administration.

Tillerson’s formal appeal of the Office of Management and Budget’s initial budget proposal seeks to restore some of the huge cuts proposed by the White House for State Department and foreign assistance funding, according to an internal State Department memo I obtained. The memo says that Tillerson is mindful of the president’s promise to make government leaner and more accountable and that he understands OMB’s mission to find savings.

“However, he is deeply concerned about the timing and the size of the reductions and he will appeal to rationalize and reduce our size and structure in a matter that makes us leaner and more efficient,” it reads. “We intend to make the strongest argument possible in our appeal that the Department needs this additional funding to ensure the United States remains active, engaged and influential throughout the world and that any changes to our mission or way or doing business occur in the context of the National Security Strategy.”