Within barely 48 hours of Ukrainian President Petro Poroshenko discussing plans with his Russian counterpart Vladimir Putin for a supposed unilateral cease-fire, the US-backed regime in Kiev has launched the most intensive combat operations yet in its two-month-old “anti-terrorist operation” to crush opposition in war-torn eastern Ukraine.

The ceasefire proposed by Poroshenko consisted in practice of an ultimatum for self-defense forces that have opposed the regime brought to power in the US-backed and fascist-spearheaded coup last February to either lay down their arms or face attack. In addition, he made clear that the supposed truce would come only after Kiev’s military had succeeded in sealing the country’s eastern border with Russia and expelling all of the volunteers who have come from Russia and elsewhere to join in the defense of the eastern regions of Donestsk and Luhansk.

The ultimatum was delivered in the form of leaflets contained in shells fired by heavy artillery into Krasny Liman, a town of 28,000 just east of the rebel stronghold of Slavyansk. The leaflet delivered a three-hour ultimatum for the local fighters to lay down their arms and surrender. If they failed to do so, it warned: “You will all be destroyed! There will be no further warnings!”

A separate leaflet warned residents that the rebels would attempt to “hide” behind them and that they should all leave immediately. This warning amounted to a prepared alibi for the massacre of civilians.

The anti-Kiev militias have universally rejected the ultimatum. “This proposal by Poroshenko to lay down our arms is simply a tactical ploy,” Myroslav Rudenko, a spokesman for the self-proclaimed Donestsk People’s Republic, told Russia’s Interfax news agency. “If people fall for it, there will be a new mopping-up operation. We will not put our weapons away.”

The New York Times quoted a member of a local defense militia in Donetsk as saying that he and others would be arrested as soon as they dropped their weapons. “What peace can they possibly offer me?” he asked. “If they want peace, then they can leave.”

One military source told Reuters that up to 4,000 local fighters were involved in the battle Thursday which involved air strikes, artillery barrages and armored assaults by the Kiev forces.

“We beat off the first attack and destroyed one tank,” Igor Strelkov, a senior rebel commander, said in a video posted online. “But it is difficult to take on 20 tanks. The battle is going on. Our people are holding but we can’t rule out that they (government forces) will break through.” Strelkov added that his forces had suffered “heavy losses” and urged Russia to “take some measures.”

As of Wednesday, at least 356 people, including 257 civilians, had been killed since the start of the Kiev regime’s “anti-terrorist operation” in eastern Ukraine,” according to the United Nations Special Commission on Ukraine. It said that among the dead were at least 14 children. The report was written to suit Washington’s policy, making no mention of how many of these civilians were victims of the government’s bombing and shelling and even referring to the unarmed men, women and children killed in last month’s fascist-led massacre at Odessa’s Trade Union House as “50 pro-Russia gunmen.”

On Wednesday, thousands of people marched through the city of Donetsk chanting “no war” in protest against Kiev’s military operations in the area. The demonstration was led by miners from coal mines in Donetsk, Gorlovka, Yenakiyevo, Snezhnoye and Torez.

The latest military assault in the east of the country came only hours after US Vice President Joe Biden called Poroshenko, praising his “commitment to move ahead with his peace plan.” He added the threat that “the US would work with our partners to impose further costs on Russia if it continued on its current course” over the Ukraine crisis.

This was followed by further threats Thursday from US Treasury Secretary Jacob Lew at a news conference in Berlin following a meeting with his German counterpart, Finance Minister Wolfgang Schäuble.

“We are in a moment where Russia has a fundamental choice to make,” Lew said at the press conference. “We certainly hope that Russia will take the discussions between President Poroshenko and President Putin seriously and move to a diplomatic resolution. But Russia has to understand that if it goes the other way there will have to be additional consequences.”

Washington is portraying the Putin government in Moscow as bearing full responsibility for the popular revolt in eastern Ukraine, which was, in fact, triggered by the US-orchestrated coup last February in which violence by extreme right-wing and neo-fascist elements succeeded in ousting the country’s elected president, Viktor Yanukovych.

This has included fresh and unsubstantiated charges that Russia is once again reinforcing its military forces on the Ukrainian border, described Thursday by NATO Secretary General Anders Fogh Rasmussen as a “very regrettable step backwards.”

In reality, the Putin government has repeatedly taken a conciliatory approach to Poroshenko, a billionaire oligarch and so-called “chocolate king,” whose election it recognized despite the effective disenfranchisement of the largely ethnic-Russian east of the country. Reflecting the interests of the layer of wealthy oligarchs that forms his government’s key constituency, Putin is anxious to avoid further economic sanctions and to defuse unrest that could spill across the Ukrainian border into Russia.

The Russian Ministry for Emergency Situations reported Thursday that the number of Ukrainian refugees fleeing the fighting into Russia has now risen to nearly 19,000.

But at every point, the Kiev regime—acting on the instructions of Washington—has taken the most provocative position.

The Washington Post, meanwhile, published an editorial Thursday warning that the US and its allies could not allow the developing debacle in Iraq to distract them from continuing and escalating the aggressive policy directed against Russia in Ukraine.

Noting that the Ukrainian president “is supervising a military effort to reassert control over Ukraine’s restive east,” the editorial declared, “If Mr. Poroshenko’s generous peace effort does not elicit a fair response, the United States and its European allies must be ready with a strategy and a timetable to respond decisively.”

The clear implication is that Washington and NATO should use the unrest in eastern Ukraine as the pretext for further ratcheting up a confrontation with Moscow that is aimed, in the final analysis, at eliminating Russia as an impediment to the US asserting it hegemony in Eurasia, the Middle East and globally.