President Donald Trump and his senior advisers are signaling potentially big shifts in both military and civilian space policies, and the first move could come by Monday.

In his inaugural speech, Mr. Trump alluded to the promise of accelerated manned exploration of the solar system. At the urging of advisers who have been weighing space policy changes, Mr. Trump’s inaugural speech referred to “the birth of a new millennium, ready to unlock the mysteries of space” and tackle various diseases.

No specific proposals regarding space initiatives have yet been considered by Mr. Trump, according to people familiar with the details. But aides for weeks have considered ways to create public-private partnerships fostering manned space exploration.

At the same time, retired Marine Corps Gen. James Mattis, who was confirmed by the Senate as defense secretary hours after Mr. Trump’s speech, previously signaled to the Senate Armed Services Committee that military space policies are going through a similar major reassessment.

In written responses to the panel earlier this month, the former four-star general said “both China and Russia have developed and tested a variety of antisatellite weapons that can destroy or disable” U.S. spacecraft.


Such warnings have been sounded over the years by Pentagon and military brass. Echoing those sentiments, Gen. Mattis said “we must ensure the availability, security and resiliency of our [space] assets at all times and through all phases of conflict.”

But answering a committee question about whether he favored introducing U.S. offensive capabilities into space, he opened the door to such a controversial move. “Offensive space capabilities should be considered to ensure survivable and resilient space operations necessary for the execution of war plans,” the defense secretary designee said in his prepared answer.

Upon confirmation, he added, “I will examine the feasibility of integrating such considerations into existing national security policy.”

That stance appears to go beyond current U.S. policy positions, which have avoided militarizing space and emphasized jawboning and using international treaties to try to prevent adversaries from deploying antisatellite weapons. So far, most of the Pentagon’s emphasis and extra funding have been directed at “hardening” future U.S. national-security satellites against potential attacks, rather than publicly advocating offensive capabilities to attack satellites of other nations.


Opponents of introducing offensive weapons into orbit contend they threaten to violate international treaty obligations and would touch off dangerous new military rivalries outside the atmosphere.

By Monday, according to people familiar with the details, Mr. Trump is expected to sign an executive order reviving a White House space council, to be chaired by Vice President Mike Pence. The aim is to reinvigorate NASA’s exploration efforts and to better coordinate U.S. military and civilian space programs

Mr. Trump also named Erik Noble, a former campaign aide with a background in space research, as the White House’s senior adviser inside the National Aeronautics and Space Administration. As expected, Gregory Autry, a University of Southern California professor and champion of commercial space ventures, was picked as the liaison between the White House and the agency.

The appointments follow a series of meetings between top transition aides and champions of commercial space projects, including entrepreneur Elon Musk, founder of Space Exploration Technologies Corp., commonly called SpaceX.


Taken together, the developments indicate Mr. Trump’s inner circle, including senior counselor Steve Bannon, are considering significant strategy changes intended to enhance space efforts. The potential shifts anticipate an era of constrained budgets and a stepped-up Pentagon drive to maintain U.S. superiority in space.

The Trump team’s deliberations come amid warnings by Sen. John McCain of Arizona, the Republican chairman of the Senate Armed Services Committee, that threats to U.S. satellites have developed “with alarming speed.” As part of a sweeping Pentagon budget blueprint Sen. McCain released earlier this week, he said that over the next five years “space must be a priority for additional funding,” and “many of these investments will, by necessity, be classified.”

Write to Andy Pasztor at andy.pasztor@wsj.com