For the past several months, the Trump administration has insisted in court that it has no control over the nearly 140 Venezuelan immigrants it deported to a prison in El Salvador this spring under the powers of a rarely used wartime statute.

Both in filings and at hearings, Trump officials have asserted that because the men are being held by jailers in El Salvador, the Salvadoran government has control over their fate. The administration has repeatedly made that claim to argue that it has no real authority to bring the immigrants back itself.

On Monday, however, lawyers for the Venezuelan men produced a document indicating that the government of El Salvador recently told the United Nations that it, in fact, bears no legal responsibility for the men. The document, written in response to a U.N. inquiry examining some of the deportations, also claimed that the Salvadoran government was merely doing the United States’ bidding when it accepted the men into its prison system.

“The actions of the state of El Salvador have been limited to the implementation of a bilateral cooperation mechanism with another state, through which it has facilitated the use of the Salvadoran prison infrastructure for the custody of persons detained within the scope of the justice system and law enforcement of that other state,” the document said.

“In this context,” it went on, “the jurisdiction and legal responsibility for these persons lie exclusively with the competent foreign authorities, by virtue of international agreements signed and in accordance with the principles of sovereignty and international cooperation in criminal matters.”