North Korean forces are experiencing mass casualties on the front lines of Russia's war against Ukraine, with a thousand of their troops killed or wounded in the last week alone in Russia's Kursk region, White House spokesperson John Kirby told reporters on Friday.

The number far exceeds the figure U.S. officials have previously provided, Reuters reported.

"It is clear that Russian and North Korean military leaders are treating these troops as expendable and ordering them on hopeless assaults against Ukrainian defenses," Kirby said, describing the North Korean troops' offensive as "massed, dismounted assaults."

North Korea's mission to the United Nations in New York did not immediately respond to a request for comment, and Russia's U.N. mission declined to comment.

Ukrainian President Volodymyr Zelenskiy, in his nightly video address, said North Korean forces had sustained "very significant" losses and were being sent into battle with only minimal protection from the Russian forces.

"We see that neither the Russian military nor their North Korean overseers have any interest in ensuring the survival of these North Koreans," he said.

"Everything is set up so that it is impossible for us to capture them. There are instances in which they are executed by their own forces. Russians send them into assaults with minimal protection."

He said Ukrainian forces had managed to take a few North Korean soldiers prisoner "but they were severely wounded and it was not possible to save their lives."

Koreans should not be losing their lives in a war in Europe, he said, and if China was sincere in not wanting the war to expand, "it needs to exert appropriate pressure on Pyongyang."

On Monday, Zelenskiy said more than 3,000 North Korean soldiers have been killed and wounded in Kursk region. He said he was citing preliminary data.

On Dec. 17, a U.S. military official said North Korea had suffered several hundred casualties in Kursk region.

Asked about what ranks the North Korean casualties included, the military official, speaking on the condition of anonymity, said it was from lower-level troops to "very near to the top."

In his comments, White House spokesperson Kirby said President Joe Biden would likely approve another security assistance package for Ukraine in coming days.

Earlier this week, Biden condemned Russia's Christmas Day attacks on Ukraine's energy system and some of its cities and asked the Defense Department to continue its surge of weapons to Ukraine.

Reuters was unable to independently verify reports of combat losses or accounts from either side.

Russian air defences downed an Azerbaijan Airlines plane that crashed in Kazakhstan, killing 38 people, Reuters reported citing four sources with knowledge of the preliminary findings of Azerbaijan's investigation into the disaster.

Flight J2-8243 crashed on Wednesday in a ball of fire near the city of Aktau in Kazakhstan after diverting from an area of southern Russia where Moscow has repeatedly used air defence systems against Ukrainian drone strikes.

The Embraer passenger jet had flown from Azerbaijan's capital Baku to Grozny, in Russia's southern Chechnya region, before veering off hundreds of miles across the Caspian Sea.

It crashed on the opposite shore of the Caspian after what Russia's aviation watchdog said was an emergency that may have been caused by a bird strike.

Officials did not explain why it had crossed the sea. The nearest Russian airport on the plane's flight path, Makhachkala, was closed on Wednesday morning.

One of the Azerbaijani sources familiar with Azerbaijan's investigation into the crash told Reuters that preliminary results showed the plane was struck by a Russian Pantsir-S air defence system. Its communications were paralysed by electronic warfare systems on the approach into Grozny, the source said.

"No one claims that it was done on purpose. However, taking into account the established facts, Baku expects the Russian side to confess to the shooting down of the Azerbaijani aircraft," the source said.

Three other sources confirmed that the Azeri investigation had come to the same preliminary conclusion. Russia's Defence Ministry did not respond to a request for comment.

A U.S. official told Reuters on Thursday there were early indications a Russian anti-aircraft system may have struck the plane. Canada said it was deeply concerned by reports that Russian air defence may have struck the aircraft.

"We call on Russia to allow for an open and transparent investigation into the incident and to accept its findings," the Canadian foreign ministry said in a statement on X.

Kazakh Deputy Prime Minister Qanat Bozymbaev said he could neither confirm nor deny the thesis that Russian air defences downed the plane.

Asked about the possibility that Russian air defences shot at the plane, the Kazakh transport prosecutor for the region where the plane came down said the investigation had yet to reach a firm conclusion.

The Kremlin, asked before the Reuters report about the idea that the aircraft had been shot at by Russian air defences, said it would be improper to comment until the inquiry was concluded.

"It is wrong to build hypotheses before the conclusions of the investigation," Kremlin spokesman Dmitry Peskov said.

WRECKAGE

Footage shot by passengers on the plane before it crashed showed oxygen masks down and people wearing life vests. Later footage showed bloodied and bruised passengers climbing out of the plane. There were 29 survivors.

Pictures of the plane wreckage showed what appeared to be shrapnel damage to the tail section of the plane.

Aviation security firm Osprey Flight Solutions said in an alert to airlines on Wednesday that footage of the wreckage and the circumstances around the air space in southwest Russia indicated the possibility that the airliner was hit by some form of anti-aircraft fire.

Ukrainian military drones have repeatedly targeted Russia's southern regions in recent months, triggering Russian air defences. Russia and Ukraine have been at war since Moscow's invasion of its neighbour in February 2022.

Earlier on Wednesday, the Russian Defence Ministry had reported the downing of 59 Ukrainian drones over several regions.

Some were reportedly shot down in closed air space over regions bordering Ukraine, including the Sea of Azov. Flight operations were reportedly temporarily suspended at Russia’s Kazan Airport due to the activity.

In addition, publicly available ADS-B flight tracking data shows that the Azerbaijani aircraft experienced GPS jamming throughout its flight over southwest Russia, the alert said.

Russia uses advanced electronic jamming equipment to confuse Ukrainian drone location and communication systems and a large number of air defence systems have been deployed to shoot down the drones.

Fourteen members of the Syrian police were killed in an "ambush" by forces loyal to the ousted government in the Tartous countryside, the transitional administration said early on Thursday, as demonstrations and an overnight curfew elsewhere marked the most widespread unrest since Bashar al-Assad's removal more than two weeks ago.

Syria's new interior minister said on Telegram that 10 police members were also wounded by what he called "remnants" of the Assad government in Tartous, vowing to crack down on "anyone who dares to undermine Syria's security or endanger the lives of its citizens," Reuters reported.

Earlier, Syrian police imposed an overnight curfew in the city of Homs, state media reported, after unrest there linked to demonstrations that residents said were led by members of the minority Alawite and Shi’ite Muslim religious communities.

Reuters could not immediately confirm the demands of the demonstrators nor the degree of disturbance that took place.

Some residents said the demonstrations were linked to pressure and violence in recent days aimed at members of the Alawite minority, a sect long seen as loyal to Assad, who was toppled by Sunni Islamist rebels on Dec. 8.

Spokespeople for Syria’s new ruling administration led by the Hayat Tahrir al-Sham (HTS) group, a former al Qaeda affiliate, did not immediately respond to requests for comment on the curfew.

State media said the curfew was being imposed for one night, from 6 pm local time (1500 GMT) until 8 am on Thursday morning.

The country's new leaders have repeatedly vowed to protect minority religious groups, who fear the former rebels now in control could seek to impose a conservative form of Islamist government.

Small demonstrations also took place in other areas on or near Syria’s coast, where most of the country’s Alawite minority live, including in Tartous.

The demonstrations took place around the time an undated video was circulated on social networks showing a fire inside an Alawite shrine in the city of Aleppo, with armed men walking around inside and posing near human bodies.

The interior ministry said on its official Telegram account the video dated back to the rebel offensive on Aleppo in late November and the violence was carried out by unknown groups, adding whoever was circulating the video now appeared to be seeking to incite sectarian strife.

The ministry also said some members of the former regime had attacked interior ministry forces in Syria’s coastal area on Wednesday, leaving a number of dead and wounded.