Is it true that the United States paid to have Abp. Oscar Romero inated?

It's a bit murkier than that, the US, via the CIA was funding right-wing terrorists in El Salvador. They also offered training and military support at the "School of the Americas" a facility in the US where counter-insurgents, right-wing anti-communists etc received training in becoming ins amongst other things. A graduate of the School of the Americas, Roberto D'Aubuisson who also led death squads in El Salvador was held responsible.