Correction: An earlier version of this editorial incorrectly identified an Air Force plane scheduled for elimination in President Obama’s 2015 budget as “the A-6 attack plane.” It is the A-10 Warthog. The corrected version is below.

IF, AS the Obama administration is convinced, the United States will no longer conduct “long and large stability operations” in foreign countries, then the defense budget it has proposed for next year makes some logical choices. Troop strength, particularly in the Army, is being cut — to the lowest level since before World War II — so that money can be spent on new technology, cyber operations and special operations forces, which will be expanded.

Weapons systems good for fighting ground wars, like the A-10 Warthog plane, are being eliminated in favor of strategic systems like the new F-35 plane and development of a new long-range bomber. Funding for missile defense is staying roughly level while the old U-2 spyplane is being grounded.

The Pentagon is also making another run at trimming the excessive personnel and basing costs that are displacing needed spending on troops and readiness as the overall budget decreases. Modest increases to the health-care payments asked of troops and retirees, trims in subsidies for housing and commissaries and another round of base closings all are justified and desperately needed.

Mostly likely, though, Congress won’t agree to those, which brings us to the not-so-rational aspects of the administration plan. It counts not only on politically tough decisions legislators are unlikely to make in an election year, but also on large new increases in defense spending above the level agreed on in the last bipartisan budget deal. For next year’s budget, the administration is hoping Congress will approve $26 billion in extra defense spending over the $496 billion request as part of a $58 billion “opportunity, growth and security initiative.” Since President Obama proposes to fund this in part by closing tax loopholes, its prospects are not good.

Pentagon plans for the following year call for a $35 billion spending increase, to $536 billion. Overall the administration counts on $115 billion in additional funding through 2019 above the levels currently written into the law. What happens if the sequester returns after next year? Secretary of Defense Chuck Hagel and the service chiefs don’t appear to have a plan, other than to warn of dire consequences.

We don’t disagree with their assessments. As it is, even if the requested budget for next year is fully funded the administration’s ability to pursue its biggest strategic priority — a “pivot” to Asia — will be weakened. The Navy will continue to shrink, with a net loss of five ships, and 11 cruisers will be placed in “reduced operating status” while they are being refurbished. The full 11-group aircraft carrier fleet will be kept but maintenance on one, the George Washington, is being deferred; if the $6 billion cost cannot be found in the next year the ship could be retired.

In sum, the new defense budget is a patch constructed on the hope that funding needed to sustain even this administration’s constrained strategic objectives can be found in future years. And what if Mr. Obama is wrong, and the United States is forced into a large land operation — in Syria, Iran, Korea or maybe Eastern Europe? The chances might be small; but if the worst occurs, the United States will not be ready.