How did the congress try to change the buying and selling slaves

In 1819 congress passed yet another act that dramatically changed the regulation of the trade. first, it authorized the president to send "armed vessels of the United States to be employed to cruise on any of the coasts of the United States or the coast of Africa" to interdict slave trades. this was the beginning of what became known as the African Squadron, which patrolled the waters off the coast of Africa in an attempt to stop the slave trade at its source.