Supplies will likely last; we’d just like to skip the slow, grinding attrition phase.
Literally: quick – battle – instant – decide
Alternately: In war, striking right away at the enemy’s main force in an attempt to end things as soon as hostilities have begun. By extension, any attempt to deal with a given task or situation quickly. Taking action immediately. Blitz tactics.
Notes: A close synonym is 短期決戦 (tanki kessen), “short-term decisive battle.”