When did General Henry W Halleck decide that it was vital to secure Kentucky in order to end Confederate incursions there?

General Henry W. Halleck recognized the importance of securing Kentucky as early as 1861, particularly after the Confederacy established a foothold in the state. By September 1861, he emphasized the need to control Kentucky to prevent Confederate advances and protect Union supply lines. This strategic decision was influenced by Kentucky's location and resources, making it crucial for both Union and Confederate forces.