When reagan took office, he increased spending dramatically. the ussr tried to keep up, but its economy was too weak. eventually, gorbachev and reagan came together to put an end to the cold war?

The answer is Defense Spending

President Regan consistently asked for an increase in defense spending of more than 10% a year.

The United States economy was far larger than USSR, and President Regan's economic policies had further helped to spur economic growth in the country.

There was new found confidence on which Regan increase defense  spending and to ensure they could have military superiority over USSR.