Industry groups are calling on President Barack Obama to protect aerospace and defense positions as he prepares a job-generating plan and lawmakers prepare to weigh more Pentagon budget cuts.

The Aerospace Industries Association (AIA) and International Association of Machinists and Aerospace Workers (IAM&AW) say in a Sept. 1 letter to Obama they are “concerned that reductions in federal spending could have harmful, if not catastrophic, consequences to our current and future national security, economy and workforce.”

Obama plans to unveil on Thursday a major initiative for generating more U.S. jobs. Congress returns to Washington this week, and the new congressional Joint Select Committee on Deficit Reduction, created via the deficit-reduction law Obama signed last month, is expected to announce its first meeting. If the panel and Congress don’t agree on additional long-term budget cuts by the end of the year, the Pentagon would be cut by up to $600 billion, in addition to its share of $350 billion in 10-year defense-related cuts already approved.

The aerospace and machinist trade groups argue in their letter to Obama that an additional $600 billion in cuts would “devastate” the aerospace and defense industry. They maintain there is a “very real risk of returning to the days when our military was described as a ‘hollow force.’”

They warn that budget cuts “disproportionally” impacting defense research and procurement would leave troops with equipment worn by decades of war. They note that, for the first time in a century, no new manned military or rotorcraft aircraft are being designed. The aerospace and defense infrastructure to replace aging combat planes is the smallest it has been since World War II, they add.

“Without new program starts, our national ability to build cutting-edge equipment will simply wither for lack of use,” the aerospace and machinist groups argue. They highlight military modernization efforts of nations like China and Russia, and the increasing competition from other nations for making military equipment.

As Obama prepares to deliver his major jobs speech, the groups note the defense and aerospace industry employs roughly 800,000 workers and supports 2 million related jobs.

They write they “urge” Obama to “consider the vital role that our second to none aerospace and defense industry has played in America’s global leadership,” noting the impact the industry has had on U.S. trade and bottom line.