The CONGRESS under Reagan did not do this. You may recall that the United States Congress is a co-equal body independent of the Execuitive Branch with it's own duties under the Constitution.
The deal Congress made with Reagan was to cut domestic spending in parallel with the tax cuts to avoid any deficit.
The Democrat dominated Congress broke that deal immediately.
The fact of the matter is that the increased federal revenues from the tax cuts far outpaced the necessary military spending, but could not keep pace with the unnecessary domestic spending.