Russia on Friday condemned as politically biased the U.S. prosecution of arms dealer Viktor Bout and said the case will remain a priority in its relationship with the United States. A defense lawer, meanwhile, said extradition won't be sought for Bout, who was sentenced to 25 years in prison Thursday, because he still stands a chance of being exonerated.

We do not ask for his extradition to serve the sentence in Russia, lawyer Viktor Burobin told news agency Itar-Tass a day after Bout's sentencing by a New York federal judge. Bout was convicted last year in connection with a U.S.-led sting operation in Thailand involving informants posing as Colombian guerrillas.

Burobin repeated Bout's claims of innocence and said defense lawyers intend to appeal his November 2011 guilty verdict all the way to the U.S. Supreme Court if necessary.

This is a very long procedure, he said. But the most important thing is that Bout intends to defend himself further. He called me up and had an optimistic voice. So we will fight further.

Meanwhile, Russia's government again denounced the U.S. prosecution of Bout as groundless and unfair.

Despite the insubstantial evidence and the illegal grounds of his arrest ... the U.S. legal authorities, which fulfill an obvious political contract, neglected the arguments of lawyers and numerous addresses at various levels in defense of the Russian citizen, the Ministry of Foreign Affairs said in a statement. Bout was declared the Merchant of Death by the U.S. authorities long before the verdict and even nearly an international terrorist, and the indictment was based only on 'criminal intentions' attributed to him.

Russia, the minstry added, will take all necessary efforts ... using all available international and legal instruments to get its citizen returned to his native country. The foreign ministry's statement didn't indicate if Russia would seek to have Bout extradited from U.S. soil even if his criminal conviction stands.

This issue certainly remains among our priorities on the Russian-U.S. agenda, the ministry said.

Thursday's sentencing came five months after Bout, 45, was found guilty by a U.S. District Court jury in Manhattan of attempting to sell weapons to the Revolutionary Armed Forces of Colombia, or FARC, which the United States considers a terrorist group bent on killing Americans.

Bout was busted in a 2008 sting operation in Thailand, where informants working undercover for the U.S. Drug Enforcement Administration posed as FARC members.

The Russian citizen spent more than two years in a Thai jail until his extradition to New York in 2010. At his trial last fall, Bout repeatedly denied the allegations against him while defense attorney Albert Dayan told jurors that Bout was an honest businessman who had only attempted to sell two old cargo airplanes for $5 million.

Bout also was ordered to forfeit $15 million by Judge Shira Scheindlin on Thursday. 

The judge denied federal prosecutors the life sentence they had sought for Bout, whose tale inspired the 2005 movie Lord of War starring Nicolas Cage.

The 25-year term for conspiring to acquire and use anti-aircraft missiles was made concurrent with similar prison sentences on charges of conspiring to kill U.S. citizens and officers, and providing support for a terrorist group.

At one point during his sentencing, when a prosecutor said Bout had agreed to sell arms to kill Americans, the Russian-speaking defendant shouted, through a translator, It's a lie! Bout told Scheindlin: I never intended to kill anyone. I never intended to sell any arms to anyone. He added, God knows this truth. 

Prosecutors said the phony FARC deal with the undercover DEA informants involved 800 surface-to-air missiles, 30,000 AK-47 assault rifles, five tons of C-4 explosive and 10 million rounds of ammunition -- artillery worth millions of dollars that would be the envy of some small countries, U.S. Attorney Preet Bharara said after the jury verdict in November.

After Thursday's sentencing, Bharara said Bout has been international arms trafficking enemy number one for many years, arming some of the most violent conflicts around the globe. He was finally brought to justice in an American court for agreeing to provide a staggering number of military-grade weapons to an avowed terrorist organization committed to killing Americans. Today's sentence is a fitting coda for this career arms trafficker of the most dangerous order.

Bout had been a notorious and prolific arms dealer since the 1990s.  His weapons -- allegedly transported via his aircraft fleet -- have been sold in conflict zones such as Liberia, the Democratic Republic of Congo, Sierra Leone and Afghanistan.

The United Nations froze Bout's assets because he had backed the brutal regime of Liberian leader Charles Taylor. Bout's support was an effort to gain illicit access to diamonds, the U.N. alleges.

His life in the illegal-arms trade was detailed in the book Merchant of Death, published two years after the Lord of War movie.

In a telephone interview with the government-run Voice of Russia, published Wednesday, Bout said he was a trophy for DEA agents. He maintained his innocence while awaiting the possibility of life in prison.

Look, even an agent in the first arrest stopped to say, 'Oh, we saw the movie about you, we are so excited, let us take a picture with you,' Bout said from from his New York jail cell as he awaited sentencing. It's like a trophy for them; I am like a hunted deer whom they killed and now they want to take a picture. Like I'm some wild animal and now they caught me and they're going to put me in their kitchen and show their kids and their grandkids and say, 'Oh, we hunted that animal.'