By Patricia Zengerle
WASHINGTON, Feb 2 (Reuters) - U.S. military leaders said on Tuesday it will take years before women are fully integrated into combat positions, although they voiced strong support for the plan to skeptical members of the U.S. Congress.
"Full integration will likely take several years," Patrick Murphy, acting secretary of the U.S. Army, told a Senate Armed Services Committee hearing.
Mark Milley, the Army chief of staff, estimated that full integration of women would take "no less than one to three years of deliberate effort."
President Barack Obama's defense secretary, Ash Carter, announced in December that the military would let women serve in all combat roles, a historic announcement greeted with intense skepticism by many Republican members of Congress.
Republican Senator John McCain, the committee's chairman, objected to the announcement at the time. He said it would have "a consequential impact" on U.S. forces and their war-fighting capabilities.
At Tuesday's hearing, McCain again expressed doubts, saying he worried there had not been enough planning before the announcement. "I am concerned that the department has gone about things backwards," McCain said.
Some Republican critics of the plan have said they fear it would lead to the imposition of quotas mandating a specific number of women in some units.
Secretary of the Navy Ray Mabus rejected that suggestion as "unacceptable," adding, "It would endanger not only the safety of Marines, but also the safety of our nation."
Many Democrats have expressed strong support.
Senator Jack Reed, the top Democrat on the panel, said physical abilities alone do not determine whether a military unit is effective.
"Fighting and winning wars, as I'm sure our panelists know well, involves much more than that," Reed said. (Reporting by Patricia Zengerle; Editing by Dan Grebler)