Defense Secretary Jim Mattis with Iraqi Minister of Defense Arfan al-Hayali at the Ministry of Defense in Baghdad on Feb. 20. (Tech. Sgt. Brigitte Brantley/Defense Department via European Pressphoto Agency)

Now is not the time to slash U.S. foreign aid, more than 120 retired generals and admirals said Monday in a letter to lawmakers, while citing past comments from Defense Secretary Jim Mattis to buttress their case.

The letter was released by the U.S. Global Leadership Coalition, which includes business executives, foreign-policy experts and retired senior military officials, as the Trump administration signaled that it will slash international spending while boosting funding for the U.S. military. The signatories include several past service chiefs and combatant commanders.

“The State Department, USAID, Millennium Challenge Corporation, Peace Corps and other development agencies are critical to preventing conflict and reducing the need to put our men and women in uniform in harm’s way,” the letter said. “As Secretary James Mattis said while Commander of U.S. Central Command, ‘If you don’t fully fund the State Department, then I need to buy more ammunition.’”

The letter added that while the military will “lead the fight against terrorism on the battlefield,” it needs strong partners to combat issues that drive extremism, including insecurity, injustice, hopelessness and lack of opportunity.

“We urge you to ensure that resources for the International Affairs Budget keep pace with the growing global threats and opportunities we face,” the letter concluded. “Now is not the time to retreat.”

The letter was addressed to Speaker of the House Paul D. Ryan (R-Wis.), Senate Majority Leader Mitch McConnell (R-Ky.), House Minority Leader Nancy Pelosi (D-Calif.) and Senate Minority Leader Charles E. Schumer (D-N.Y.). It was released as administration officials said that Trump will announce Tuesday a 10 percent boost in military spending, with a corresponding cut to other federal agencies. Foreign aid, in particular, is expected to face significant budget cuts, as Trump follows through on his agenda.

The quote from Mattis cited in the letter came in March 2013 during a hearing before the Senate Armed Services Committee a few months before he retired from the Marine Corps. It came in response to a question from Sen. Roger Wicker (R.-Miss.), who inquired whether the U.S. international development budget was helpful to the United States, and has often been used since by advocates for “soft power.”

“Yes, sir,” Mattis said at the time. “I would start with the State Department budget. Frankly, they need to be as fully funded as Congress believes appropriate, because if you don’t fund the State Department fully then I need to buy more ammunition ultimately. So I think it’s a cost-benefit ratio. The more we put into the State Department’s diplomacy, hopefully the less we have to put into a military budget as we deal with the outcome of apparent American withdrawal from the international scene.”

Many of the officers who signed the letter retired within the past few years, and some led U.S. forces in combat. They include Marine Gen. John R. Allen, the former top U.S. commander in Afghanistan; Army Gen. Pete Chiarelli, vice chief of staff of the Army from 2008 to 2012; Marine Gen. James T. Conway, commandant of the Marine Corps from 2006 to 2010; Adm. Jonathan Greenert, chief of naval operations from 2011 to 2015, and Adm. Eric T. Olson, the chief of U.S. Special Operations Command from 2007 to 2011.

At least two officers who signed the letter have previously met with Trump and offered advice on other issues. They are Army Gen. David H. Petraeus, who led troops in Iraq and Afghanistan before serving as director of the Central Intelligence Agency from 2011 to 2012, and Adm. James G. Stavridis, who retired as chief of U.S. European Command and supreme allied commander of the North Atlantic Treaty Organization in 2013.