A military court in southern Russia on Wednesday held the first full hearing in the trial of four Crimean Tatars accused of joining a radical Islamist group.

Armed officers from Russia's FSB security service detained the men in raids on homes in the Crimean town of Bakhchysaray on May 12.

Ukrainian pilot Nadiya Savchenko, freed from a Russian jail this week, on Friday said she is ready to negotiate with pro-Russian separatists on releasing prisoners.

"I am ready to talk to the devil himself to get every one of our people back," she said at her first news conference since her dramatic release, part of a prisoner swap with Moscow that drew a line under a major diplomatic spat.

Ukrainian pilot Nadiya Savchenko, who was freed from jail in Russia as part of a prisoner exchange on Wednesday, has been condemned by Moscow as a murderer but is viewed by many in her Western-friendly country as a national hero.

The 35-year-old army helicopter navigator was handed a 22-year jail sentence in March over the killing of two Moscow state television journalists in the conflict in east Ukraine.

Ukrainian pilot Nadiya Savchenko has been freed after nearly two years in a Russian prison and is expected to return to a hero's welcome to Kiev shortly, defense laywers said Wednesday.

Savchenko's defense team confirmed Savchenko was on her way to Ukraine and thanked the pilot's supporters. "She is on her way home, to Ukraine," lawyer Mark Feigin said on Twitter.

The Pentagon on Friday rejected a Russian proposal to launch joint air strikes against jihadists from next week in Syria, where they have been conducting separate bombing campaigns.

"We do not collaborate or coordinate with the Russians on any operations in Syria," Pentagon spokesman Navy Captain Jeff Davis told reporters, explaining that Washington and Moscow have separate military objectives.

Britain, France, the United States and Ukraine on Tuesday blocked a Russian request to add two Syrian rebel groups to a U.N. terror blacklist and sideline them from the Syrian peace process, diplomats said.

Russia had requested that Jaish al-Islam (Army of Islam) and Ahrar al-Sham be added to the sanctions list for their ties to al-Qaida and the Islamic State group.

Russian President Vladimir Putin on Tuesday said there remained "a lot left to do" for the forces of Syrian leader Bashar Assad despite Russian firepower hitting over 30,000 targets in the war-torn country.

Iran's army is now equipped with a Russian air defense system after a long and controversial delivery process, Defense Minister General Hossein Dehghan was quoted as saying Tuesday.

"I inform our people that... we are in possession of the strategic S-300 system" and that it "serves our air force's counterattack command," Dehghan said, according to ISNA news agency.

Russian servicemen in sand-colored fatigues sit by phones and computer screens at a base in northwestern Syria, monitoring a ceasefire often on the brink of collapse.

In coordination with a U.S. center in the Jordanian capital, soldiers at Russia's Hmeimim airbase record breaches of the truce -- brokered by Moscow and Washington -- from barracks converted into a makeshift call center.

Russia's defense minister said Wednesday that Moscow will set up three new divisions in the west and south of the country by the end of the year to counter NATO forces close to its border.

"The defense ministry is taking a range of measures with the aim of countering the build-up of NATO forces in close proximity to Russia's borders," Sergei Shoigu was quoted as saying by Russian news agencies.