In fact, Byron Callan, one of Washington's most seasoned observers of defense budgeting, this week lowered his estimate of the likelihood the president's budget for next year would be adopted as presented from 10% to zero -- in other words, there's no chance at all. Callan, the senior defense analyst at Capital Alpha Partners, is also growing more skeptical that the White House can get a modest increase in defense for the current year. A growing chorus of Washington insiders say defense spending for the rest of the year will be stuck at last year's levels. 

It was an easy mistake to make, given how baroquely complicated the federal budget is and the way the White House proposes to slash domestic spending as it boosts defense. But as Byron Callan of Capital Alpha Partners pointed out, the big increase in Pentagon spending described by the White House was calculated by comparing what Trump wants to spend with what the law currently permits. Using that approach, President Obama's planned defense budget for 2018 would have looked like an oversized increase, too.

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So the last Obama spending plan for 2018 proposed a Pentagon budget of $557 billion, plus an additional $8 billion in so-called mandatory spending not covered by the budget law – for a total of $565 billion. Analyst Callan figures that if you take 5% of President Trump's proposed $54 billion increase in "defense" that would go to Department of Energy nuclear-weapons programs rather than the Department of Defense, the actual number the White House is proposing the Pentagon get in 2018 is $573 billion.