Four senior lawmakers are objecting to the Obama administration’s plans to negotiate a code of conduct with other nations for activity in space.

Among their concerns, cited in a letter to President Barack Obama, are that such a space pact would be an “international arms control agreement” that would bypass congressional input and hurt U.S. companies.

Secretary of State Hillary Clinton announced Tuesday that “the United States has decided to join with the European Union and other nations to develop an International Code of Conduct for Outer Space Activities.” It is intended to thwart risks to U.S. space systems posed by “space debris and irresponsible actors,” according to the State Department.

“A Code of Conduct will help maintain the long-term sustainability, safety, stability, and security of space by establishing guidelines for the responsible use of space,” Clinton said in a statement, citing “troubling trends that are damaging our space environment.” Those include a operations of more than 1,000 active satellites in space operated by sundry international parties.

Clinton said the United States “has made clear to our partners that we will not enter into a code of conduct that in any way constrains our national security-related activities in space or our ability to protect the United States and our allies.”

Yet Rep. Michael Turner (R-Ohio), Rep. Joe Heck (R-Nev.), Sen. Jeff Sessions (R-Ala.) and Sen. Jon Kyl (R-Ariz.) aren’t happy.

They tell Obama in a new letter they are concerned the space code of conduct would be based on a draft European Code of Conduct for Outer Space Activities, which his administration opted against signing.

“Such an international agreement could establish the foundation for a future arms control regime that binds the United States without the approval of Congress, which would bypass the established constitutional processes by which the United States becomes bound by international law,” write the lawmakers. They say they have “significant policy and operational concerns with the EU Code of Conduct, which appears to be the foundation for negotiations announced by your administration, with regard to national and economic security.”

Turner chairs the House Armed Services Committee’s Strategic Forces subcommittee, Heck leads the House Permanent Select Committee on Intelligence’s Technical and Tactical Intelligence subpanel, and Sessions is the ranking member on the Senate Armed Services Committee’s Strategic Forces subcommittee. Kyl is the Senate Republican whip.

The four lawmakers argue if the constraints imposed by such a code and Pentagon regulations “were not objectionable on a substantive or legal basis, we are deeply concerned about the unknown consequences such limitations would have on future military or intelligence programs given that the draft code appears to be of unlimited duration.” They note that “no one can know today what programs the Untied States may need to undertake in outer space in the future for its military and intelligence national security requirements.”

The four lawmakers say they are “also concerned about the potential commercial implications of such a code for U.S. employers that rely on open access to outer space.”

“As you know, the U.S. private sector has significant investment with large numbers of U.S. jobs that depend on those investments. A code such as this could negatively impact those jobs at exactly the wrong time for the U.S. economy.”