Government forces unleashed ground assaults and air bombardments throughout the region, including heavy artillery shelling around the rebel-controlled city of Slavyansk and pitched battles for control of administrative buildings in Donetsk.
The attacks began shortly after President Petro O. Poroshenko declared an end to a 10-day cease-fire and ordered government forces to renew their effort to quash a pro-Russian separatist insurrection in the east.
The recharged government offensive followed two days of conference calls with the leaders of Russia, France and Germany that failed to yield concrete steps toward a peace agreement, and came as Mr. Poroshenko accused Putin of talking about peace while arming and encouraging the separatists.
Ukraine has been in turmoil since December, when its former president, Viktor F. Yanukovych, spurned a trade deal with the European Union in favor of a $15 billion loan and other concessions from Russia.
Yanukovych was driven from office in the ensuing demonstrations, and after Putin seized Crimea in March the separatist rebellion began brewing in the east, which has historically close ties with Russia.
While President Obama and European leaders have joined Ukraine in accusing Moscow of creating and sustaining the rebellion in eastern Ukraine, Putin blamed the West for the troubles there and talked broadly about protecting Russians outside the country’s borders.
“I would like to make it clear to all: This country will continue to actively defend the rights of Russians, our compatriots abroad, using the entire range of available means — from political and economic to operations under international humanitarian law and the right of self-defense,” Putin said.
In the speech, the Russian president chastised Mr. Poroshenko for ending the cease-fire and urged renewed peace negotiations.
But Putin also described the economic sanctions against Russia by the United States and its allies as “blackmail” and said the West had precipitated the conflict in Ukraine by blithely ignoring Russia’s interests for years.
At least 27 Ukrainian soldiers had been killed in clashes with rebels since Mr. Poroshenko announced the unilateral cease-fire on June 20, putting heavy political pressure on him to resume military action and cut off negotiations with the rebels, viewed as terrorists by most Ukrainians.
Even some supporters of Mr. Poroshenko disapproved of his discussions with Putin, who is widely reviled after the invasion and annexation of Crimea this year.
European leaders issued an ultimatum to Russia last week, demanding it do more to end the violence caused by the separatists.
But attacks on government forces had continued, and with a Monday deadline passing with no progress toward a peace deal and no indication that the Europeans were prepared to move ahead with new sanctions, Mr. Poroshenko decided to end the cease-fire.
There were reports of heavy shooting and bombardments all across eastern Ukraine on Tuesday, including civilian casualties.
Gunfire cracked in the center of the regional capital of Donetsk, where rebels and government forces fought for control of the Interior Ministry headquarters and a police building came under attack by the separatists.
In the city of Kramatorsk, to the north, four people were killed when a minibus came under artillery fire, Ukrainian news agencies reported.
In a significant victory for the government, Ukrainian forces retook control of a checkpoint at Dolzhansky, in the Luhansk region, one of three important border crossings with Russia that had been seized by rebels.
European leaders demanded on Friday that the crossings be surrendered to Ukrainian authorities.
Mr. Poroshenko issued a statement congratulating his troops for reclaiming the border checkpoint.
Overnight, there were reports that two explosions damaged railroad lines in the east.
A television tower serving the besieged city of Slavyansk was destroyed by artillery fire.
Photographs posted on the Internet showed the metal lattice of the tower reduced to a tangled pile of rubble.
The resumption of military operations was cheered by many supporters of the Ukraine government.
In Kiev, Alyona Hetmanchuk, the director of the Institute of World Policy, a research organization, said that by engaging in protracted peace talks even as soldiers continued to be killed, Mr. Poroshenko had failed to live up to campaign promises that he would not negotiate with terrorists and that he would swiftly crush the insurrection.
“He was elected as a crisis manager, not as a diplomat, and even before elections he said that antiterror operations should last hours, not days or months or weeks,” Ms. Hetmanchuk said in an interview.
“People liked it and people thought he would be very decisive and he would resolve the problem within a couple of days, maximum weeks.”
Putin, in a speech to diplomats in Moscow on Tuesday, said that he and other leaders had sought to persuade Mr. Poroshenko to continue the cease-fire during the conference call on Monday, but that the Ukrainian leader had chosen war and would now bear personal responsibility for the outcome.
While Putin reiterated his pledge to defend Russian-speaking people wherever they live, he did not threaten any imminent military action or announce any redeployment of Russian forces along the Ukrainian border, as he has in other instances when tensions flared.
“Unfortunately, President Porosehnko has resolved to resume military action,” Putin said.
“We failed — when I say ‘we,’ I mean my colleagues in Europe and myself — we failed to convince him that the road to a secure, stable and inviolable peace cannot lie through war.” Putin added.
“Now he has taken the full responsibility for this, and not only military responsibility, but also political.”
Secretary of State John Kerry told his Russian counterpart on Tuesday that the United States supported Ukraine’s right of self-defense and put the blame for the renewed fighting on the separatists.
In a telephone call with Sergey V. Lavrov, the Russian foreign minister, Mr. Kerry, “expressed strong concern about the refusal of Russian-supported separatists to take the necessary steps” that “would have enabled an extension of the cease-fire,” the State Department said.
Mr. Kerry also called on Russia to stop sending arms to the separatists.
Dmytro Tymchuk, a military analyst close to the Ukrainian government, praised Mr. Poroshenko’s decision to end the cease-fire, saying that the one-sided adherence to the truce by the Ukrainian military had only strengthened rebel forces, allowing them to rearm and regroup.
“Every day the truce, whatever its political significance, provided tangible reinforcement to the terrorists from a military point of view,” Mr. Tymchuk wrote on Facebook, adding, “A longer truce period would give terrorists a chance to drastically increase their combat readiness.”
The United States and its NATO allies have accused Russia of sending tanks, artillery and other weapons to the rebels, and of allowing fighters from Russia to cross the border to join rebel militias.
Some rebel leaders had demanded a complete withdrawal of government troops from eastern Ukraine as a precondition for formal peace negotiations.
The Russian Foreign Ministry released a statement saying that peace negotiations should resume immediately and blamed the Ukrainian government for the failure of previous talks.
“We are convinced that the efforts to put the situation back on the negotiation track should be continued, including an urgent meeting of the contact group,” the ministry said.
“We will assist this in every way.”
Source: The New York Times