Moscow appears to have deployed an advanced new stealth fighter to its airbase in Syria, reports in Russian news media and online videos of the aircraft indicated on Thursday, in what analysts say could be a risky attempt to gain publicity and operational experience for the jet in one of the world’s most tangled conflicts.

Their appearance comes at a fraught moment in the seven-year war, as the US and Russia occasionally scramble jets to intercept each other over Syria and pro-regime warplanes pound the Damascus suburb of eastern Ghouta despite protests from the UN. More than 330 people have been killed there since the bombing began on Sunday, according to reports.

The deployment of two Su-57 fighter aircraft, which were filmed landing at Russia’s Khmeimim airbase along the Mediterranean coast, would represent the latest high-tech military system Russia has exhibited in Syria, a conflict that has already been used to demonstrate the prowess of Russian cruise missiles and combat helicopters.

Both the Kremlin and the Russian ministry of defence declined to comment on whether the fifth-generation Russian fighter jets, which are still in combat testing phases, had been deployed. Russian news agencies, including the respected RBC business daily, published reports on Thursday saying sources in the ministry of defence had confirmed the presence of the advanced fighter jets in Syria.

The military had previously announced it would begin testing the fighters in combat. They have been touted as a future rival to the Lockheed Martin F-22 Raptor, which the US uses in patrols over Syria.

Yuri Borisov, the deputy defence minister, said earlier in February: “We are buying Su-57 jets for test combat use. First stage state trials are over.”

US-led forces wounded and killed dozens of Russian mercenaries and pro-Assad militiamen earlier this month, in a battle near the city of Deir ez-Zor in which US drones and warplanes directly targeted Russians fighting on the government side for the first time in the war.

Russia has regularly used the conflict as a testing ground for its latest military technology and has even credited it for an uptick in arms sales. The Su-57, the first operational Russian jet to use stealth technology, has been plagued by cost and time overruns, and analysts said there could be a business rationale behind the deployment.

“There is some operational merit in doing this, but there’s also a publicity element,” said Douglas Barrie, a senior fellow for military aerospace at the International Institute for Strategic Studies in London. He noted that a successful demonstration of the plane in Syria could assuage concerns of potential buyers such as the Indian government.

It is still unclear whether the aircraft could play any role in day-to-day operations. “We haven’t seen it fire anything. We haven’t seen it drop anything,” Barrie said.

Ruslan Pukhov, a defence analyst and the director of the Moscow-based Centre for Analysis of Strategies and Technologies, said it could be risky to deploy the new jets to Syria.

“If I were the minister of defence, I probably wouldn’t do it,” he said. “If you lose one of these planes, it could make for big problems. And what happens if the technology falls into the wrong hands?”