From late 1963 to early 1965, Logevall claims, the Johnson administration faced a deliberate choice about whether it should raise or lower the stakes in  Make it an all-out test of will, which it became, or look for an excuse to leave--perhaps with the claim that the regime in the South had become too ill-behaved to be worth further U.S. support or lives.
The administration at the time had to pick whether to up or lower the stakes.
The administration at the time didn't have to pick whether to up or lower the stakes.