Former U.S. Drug Enforcement Administration officials who were involved in the effort to bring "Merchant of Death" Viktor Bout to justice have characterized his trade to Russia for WNBA star Brittney Griner's freedom as a "disgrace" and a "grave threat" to U.S national security. 

Griner, who has been held prisoner in Russia since February, was released Thursday with applause from Biden administration officials. But former DEA officials had previously spoken out against trading Bout, a convicted Russian arms dealer, for her release, and at least one former DEA special agent in charge, Derek Maltz, condemned the news as a "blow to the rule of law." 

"Americans should be very careful traveling around the world. This decision has put Americans at a huge risk," Maltz tweeted Thursday, calling Bout's arrest a "total disgrace." He had supervised the agents who secured Bout's arrest in Thailand in 2008. Before his release, Bout was serving a 25-year sentence in federal prison for his 2011 conviction on charges of conspiracy to kill Americans relating to the support of a Colombian terrorist organization. 

BIDEN DOES NOT MENTION RUSSIAN ARMS DEALER VIKTOR BOUT IN REMARKS ON BRITTNEY GRINER SWAP

Viktor Bout in jail

Alleged Russian arms dealer Viktor Bout (R) walks past temporary cells ahead of a hearing at the Criminal Court in Bangkok on Aug. 20, 2010. (CHRISTOPHE ARCHAMBAULT/AFP via Getty Images)

After reports in May indicated exchanging Bout was a possibility, one ex-official said that exchange would be "a slap in the face" to those who worked tirelessly to put him behind bars. 

Michael Braun, a former chief of operations at the U.S. Drug Enforcement Administration, wrote in an article for Foreign Policy magazine in August that Bout was "dangerous." A 35-year veteran of federal law enforcement, Braun was tasked with "ultimate oversight" over the operation that led to Bout's arrest and incarceration. 

GEN. PETRAEUS ON GRINER RELEASE: HATE TO ‘REWARD’ RUSSIA FOR SWAP, VIKTOR BOUT HAS ‘BLOOD ON HIS HANDS’

Brittney Griner in handcuffs

WNBA star and two-time Olympic gold medalist Brittney Griner is escorted from a courtroom after a hearing in Khimki, just outside Moscow, Russia, Aug. 4, 2022. (AP Photo/Alexander Zemlianichenko, File)

"Trading Bout away wouldn’t just be a slap in the face of the law enforcement officers and operatives who labored to bring Bout down, many of them risking their lives in the process. It would also pose a grave threat to the national security of the United States and its allies," Braun wrote.

He explained that Bout was a former Russian intelligence officer who entered into the arms trade in the 1990s. "By 2003, he had become the world’s pre-eminent arms trafficker, flooding weapons to U.S.-designated terrorist organizations, insurgent groups, narcotics cartels, and rogue regimes all over the world," Braun wrote.

BRITTNEY GRINER RELEASED FROM RUSSIAN PRISON IN SWAP FOR CONVICTED ARMS DEALER

Viktor Bout in 2010

Alleged Russian arms dealer Viktor Bout (C) is escorted by policemen as he arrives for a hearing at the Criminal Court in Bangkok on Aug. 20, 2010. (CHRISTOPHE ARCHAMBAULT/AFP via Getty Images)

"Bout’s vast international enterprise could 'transport tanks, helicopters and weapons by the tons to virtually any point in the world,' according to the U.S. government," he continued. "He did particular damage in Africa, where insurgent and terrorist groups slaughtered hundreds of thousands of innocents with his weapons, depicted in the Nicolas Cage film Lord of War. Weapons that Bout sold to the Taliban were used against U.S. and NATO forces in Afghanistan."

The U.S. government targeted Bout with sanctions in 2004 and in 2006 instructed the DEA to seek his arrest under counter-narcoterrorism laws. Two years later, DEA executed a sting operation in partnership with Thai police that saw Bout arrested in Bangkok. He was convicted based on explicit statements he had made conspiring to sell weapons, including man-portable surface-to-air missiles, to be used against U.S. personnel in Columbia, declaring he had been "fighting the United States … for 10 to 15 years." 

CLICK HERE TO GET THE FOX NEWS APP

Braun predicted that if released, Bout could become a Russian asset, "planning and executing clandestine supply missions in support of Russian proxies like the Wagner Group in Africa, Venezuela, and other hot spots." 

"Trading Bout would also encourage Moscow and other rogue regimes to take Americans hostage, exacerbating the precedent set by Biden’s exchange of Russian-held American Trevor Reed for another U.S.-imprisoned Russian criminal earlier this year," Braun warned. "We can expect Moscow to double down on taking Americans hostage to trade for the Russian cybercriminals—who also often moonlight for Russian intelligence—extradited to the United States by allied countries." 

Fox News reached out to Maltz and Braun for additional comment.