A U.S. Air Force B-52 at this year’s Australian International Airshow. (Paul Crock/AFP/Getty Images)

TWO PIECES of good news about U.S. defense spending: Both President Obama and congressional Republicans have recognized that cuts imposed by the 2011 “sequester” scheme are unacceptable, and both have moved to restore tens of billions of dollars in funding for next year’s budget. Two pieces of bad news: The proposed increases still face thorny political challenges — and even the revised spending plan remains far from adequate at a time when the United States has returned to war in the Middle East and faces mounting threats elsewhere.

Mr. Obama was the first to propose breaching the spending level for fiscal year 2016 mandated by the sequester, adding $34 billion to that baseline in the plan he released in January. His total of $612 billion has now been roughly matched by budget outlines passed by Republican-controlled committees in the House and Senate. If those survive floor votes in the coming days, Republican defense hawks will have succeeded in overcoming tea party conservatives who pushed to retain the sequester limits and force devastating cuts on the Pentagon.

The politics, however, remain tricky. Mr. Obama proposed matching the defense increase with an equal amount of added domestic spending, but the Republican budget plans exclude that. That may make it difficult to win the floor votes, if Democratic support is needed, and Mr. Obama might eventually resist a defense increase if there is no domestic counterpart.

The apparent consensus on a spending figure also veils some GOP budget gimmickry. While the administration added its additional defense spending to the base budget, Republicans tried to balance fiscal and military hawkishness by leaving the sequester-mandated base budget unchanged and pouring additional funds into a contingency account meant to cover temporary war expenses. That tactic has been used before, but it is a poor way to do business that may end up constricting spending on long-term defense needs. At a minimum, it means a necessary fight over the base budget will have been kicked down the road.

The urgency of adjusting that spending plan was spelled out by a bipartisan commission last summer, as well as in recent testimony from the Joint Chiefs of Staff. Thanks to the sequester and earlier cuts by Mr. Obama, defense spending has dropped more than 20 percent in real terms since 2010. The Army is headed for its lowest staffing levels since the Eisenhower era, the Navy will soon have the fewest ships in a century and the Air Force has fewer planes than it has had since its creation in 1947. Calling that reduction a “serious strategic misstep,” the National Defense Panel urged restoration of the 10-year Pentagon budget drawn up by Mr. Obama’s first defense secretary, Robert Gates. That would require tens of billions of additional spending in 2016 alone beyond the level now proposed by Mr. Obama and the budget committees.

Joint Chiefs Chairman Gen. Martin Dempsey described even that proposed level as “at the bottom edge of manageable risk to our national defense.” At a time when U.S. forces are fighting in Iraq and Syria and attempting to deter Russian aggression in Europe, that is a perilous place for it to be.