NATO chief warns Ukraine war is entering a 'more dangerous' phase that could last years as the Kremlin claims the fighting could wrap up soon

• The Kremlin said Russia's war with Ukraine could end in the "foreseeable future."
• Kremlin spokesman Dmitry Peskov said Russia's "special military operation" was succeeding, TASS reported. Russian forces have endured heavy losses.

NATO Secretary General Jens Stoltenberg on Friday warned that the conflict in Ukraine was heading into a "dangerous" new phase, as the Kremlin simultaneously claimed that Russia's unprovoked six-week war could end in the "foreseeable future."

Stoltenberg told NPR that Russian President Vladimir Putin has not "changed his overall aim, and that is to control Ukraine," warning that the war is likely to see "much heavier fighting" in the days to come.

The NATO chief said Putin was unlikely to "sit down and engage in good faith in negotiations for a political solution," adding, "Therefore, we need to also be prepared for the long haul. And it's hard to predict. Wars are always unpredictable. But this can last for months and even years."

Meanwhile, Putin's spokesperson Dmitry Peskov told reporters that Moscow's so-called "special military operation" in Ukraine could soon be over because Russia was succeeding at reaching its goals in the eastern European country, according to the Russian state-owned TASS news agency.

"The operation continues and the goals are being achieved," Peskov said, according to TASS.

Peskov added, "Substantive work is being carried out both on the military side, in terms of advancing the operation, and on the side of the negotiators who are in the negotiation process with their Ukrainian counterparts," TASS reported.

The Kremlin spokesman said during a live interview with Sky News on Thursday that the Russian military was "doing their best to bring an end to that operation."

"And we do hope that in coming days, in the foreseeable future, this operation will reach its goals or will finish it by the negotiations between Russian and Ukrainian delegation," Peskov said.

When pressed Friday by whether the war could actually end in days, Peskov said, "We are talking about the foreseeable future," according to TASS.

On Thursday, Peskov admitted that Russian forces had endured "significant losses."

Despite Ukraine's armed forces being largely outnumbered and outgunned by the Russians, the Ukrainians have put up fierce resistance, which has resulted in heavy losses for Russian troops. NATO estimates between 7,000 to 15,000 Russian troops have been killed since the war began less than two months ago. Russia has also lost an astonishing number of generals in the conflict.

As Peskov claimed the war would wind down soon, the brutal Russian onslaught continued. At least 50 people were killed on Friday — including five children — after two Russian rockets hit a train station in the eastern city of Kramatorsk that was packed with people attempting to evacuate, Ukrainian officials said.

Putin launched Russia's invasion of Ukraine on February 24, with Russian troops surrounding and shelling towns and cities across the country. Civilian areas have consistently been targeted, killing at least 1,611 and leading over 4.3 million Ukrainians to flee the country, according to the UN's latest figures.

Both Western and Ukrainian leaders have accused Moscow of committing war crimes in Ukraine, and in a rare diplomatic rebuke, Russia was suspended from the UN Human Rights Council on Thursday.

Though there's strong evidence to the contrary, Russia has repeatedly and falsely stated that it's not targeting civilian areas.

Russia has continuously spread disinformation on the war, habitually offering misleading and inaccurate assessments of the situation on the ground.

The Russian military has struggled to make major gains in the war thus far, in spite of the Kremlin's claim that the "operation" has achieved its goals.

Russia failed to take Kyiv, the Ukrainian capital, and — for the time being — has shifted its focus to the eastern Donbas region where Russian-backed separatists have been fighting Ukraine since 2014.

Stoltenberg on Tuesday warned that Russia would launch a "concentrated" offensive in the Donbas.

"In the coming weeks we expect a further Russian push in the east and southern Ukraine, to try to take the entire Donbas and to create a land bridge to the occupied Crimea," the NATO chief said.