To provide a covert aid simply means to provide aid in secrecy. The US has been using this way of funding for numerous guerrilla groups throughout the world because of their interest in certain country or region. This has been mostly the case in Latin America, as the US regularly was providing covert aid for guerrilla fighters in almost all countries in this particular region. The reason for this type of action by the US was its economic and political interest in the region, but unfortunately their actions caused much more damage than they did good, resulting in large anti-American sentiment in Latin America.
One of the key factors that prompted the change in Ronald Reagan’s approach toward the Soviet Union during his second term was the the USSR was visibly crumbling, so he could afford to be more assertive.