President Trump has suggested that Edward Snowden should return home from Russia. He later said he is considering a pardon for the former federal government contractor, who fled the United States after he blatantly stole tens of thousands of classified and sensitive documents from the National Security Agency, many of which have been publicly released.

Getting Snowden back in the country would assist intelligence officials to determine the extent in which he breached national security and colluded with foreign powers. But he should not be allowed back by the means of a pardon from the White House. Snowden is a criminal fugitive who should be judged for his actions before a pardon can be considered.

Snowden claims he is no criminal but rather a whistleblower who released classified information to expose “illegal spying” on citizens at the National Security Agency and the intelligence services of our allies. But there is no evidence that Snowden ever tried to seek whistleblower protection. Even more important, however, his declaration is patently untrue.

Snowden revealed the data collection program known as Prism, lawfully conducted under the Foreign Intelligence Surveillance Act and focused on identifying terrorists around the world with a goal of disrupting their plans. Snowden alleged that the National Security Agency abused such authority by illegally collecting and retaining information on Americans, yet no credible evidence has surfaced to back such claims.

It is hard to fathom the true extent of the damage that his treachery has done to our national security and our allies. A month before leaving for Russia, he downloaded and stole tens of thousands of highly classified documents. He also leaked some of our most sensitive information for collection platforms. This success with distributing so much classified data has made Snowden one of the most notorious traitors.

Russia has no doubt benefited from the treasure trove that he carried to Moscow in return for asylum. All the while, the United States dedicated years working to clearly understand the extent of the damage from the treasonous actions, like unauthorized removal of such highly classified information and the enabled leaks of some of that material.

The size and breadth of the intelligence breach conducted by Snowden remains unknown. We do, however, have a better sense of the gravity of the intelligence losses. The unclassified portion of a document released by Congress estimated that Snowden downloaded well over one million documents that are likely in the hands of officials in Russia.

The same report concluded that the vast majority of documents pilfered from the National Security Agency had no connection to what Snowden said was related to collection of data on Americans. The journalist Glenn Greenwald, who won a Pulitzer Prize for stories on the stolen documents, said in an interview that the disclosures included sensitive blueprints on how the National Security Agency operates. Such information can serve our adversary Russia as directions for evading surveillance.

The intelligence community is still working to understand all this damage caused by Snowden. When he illegally downloaded classified information, he did everything he could to hide his tracks, an effort made easier by the simple fact that the National Security Agency at the time lacked sufficient data removal tracking to account for such mishandled data.

Snowden should return to the United States and face prosecution for the criminal actions he has been charged with by the Justice Department. In the course of this prosecution, we stand our best chance to hear a broad account of what he removed from the National Security Agency and then what he did with those secrets that have not been released.

Trump once called Snowden a “terrible traitor” and a “terrible threat.” He was right then and he is right now to want him back in the United States. What is necessary, however, is a move that will hold him accountable for his crimes and assure that the intelligence community has a total idea of the damage that he has unleashed on our national security.