Last Updated Jun 30, 2014 6:30 PM EDT
KIEV, Ukraine - Ukrainian President Petro Poroshenko said he is halting a unilateral cease-fire in the conflict with pro-Russian separatists and that Ukrainian forces will go on the offensive against the rebels.
A statement from Poroshenko on his website early Tuesday said the cease-fire is being halted and that "we will attack and we will free our country."
The fragile cease-fire expired Monday night. The idea was to give rebels a chance to disarm and to start a broader peace process including an amnesty and new elections.
But rebels did not disarm, and the cease-fire was continually violated. Rebels did not comply with Poroshenko's latest push to get them to turn over key border crossings with Russia and permit international monitoring of the cease-fire.
"The unique chance to put the peace plan into practice was not realized," Poroshenko said in a speech prepared for delivery to the nation. "This happened because of the criminal actions of the fighters."
The recently elected Poroshenko had already extended the cease-fire from seven days as part of a plan to end the fighting that has killed more than 400 people since April.
Poroshenko's decision followed four-way talks in search of a solution with Russian President Vladimir Putin, German Chancellor Angela Merkel and French President Francois Hollande on Monday as the deadline approached. He issued a statement after the talks ended, saying the key conditions needed to continue the ceasefire had not been met.
Poroshenko said he made the decision after a meeting of the national security council. "After discussion of the situation, I, as commander in chief, took the decision not to continue the unilateral cease-fire."
"Ending the cease-fire, this is our answer to terrorists, armed insurgents and looters, to all who mock the peaceful population, who are paralyzing the economy of the region ... who are depriving people of a normal, peaceful life," Poroshenko said in his speech.
European leaders and the U.S. have urged Russia to use its influence with the rebels to ease the bloodshed and have threatened to impose another round of economic sanctions against Moscow.
While Putin has expressed support for the cease-fire, the West has accused Russia of allowing weapons and fighters to flow across the border into Ukraine. Russia says any Russians there have gone as private citizens.
Tension between Russia and Ukraine escalated in February when protests by people who wanted closer ties with the European Union drove pro-Russian President Viktor Yanukovych from office. Russia called that an illegal coup and seized Ukraine's Crimea region, saying it was protecting the rights of people there who speak Russian as their main language.
The insurrection in the eastern regions near the Russian border started soon after, with separatists occupying buildings and declaring independence.
Poroshenko said he meant for a cease-fire to be followed by an amnesty for fighters who had not considered serious crimes, and political concessions such as early local and regional elections, protections for speakers of Russian and, in the longer term, changes to the constitution to decentralize power to the regions.
The end of the cease-fire raises the question of what action the Ukrainian military can take. It has so far been unable to dislodge rebels occupying the city of Slovyansk or to retake control of three key border crossings with Russia. At one point, the rebels shot down a government military transport, killing 49 service members.