Correction: A previous version of this article misidentified Grigory Golosov as a political science professor at St. Petersburg University. Golosov is a professor at St. Petersburg European University. This version has been corrected.

Voters on Sunday handed chocolate tycoon Petro Poroshenko a commanding victory in Ukraine’s presidential election, exit polls showed, as a violence-torn nation sought to put an end to three months of geopolitical drama.

Voters on Sunday handed chocolate tycoon Petro Poroshenko a commanding victory in Ukraine’s presidential election, exit polls showed, as a violence-torn nation sought to put an end to three months of geopolitical drama.

Fight for airport in eastern Ukraine continues; president-elect calls rebels ‘pirates’

Explosions and gun battles continued to rock this separatist region of eastern Ukraine late Monday night as state security forces fought rebels for control of a major airport, hours after Ukraine’s president-elect declared in Kiev that he would seek to unite the nation after a months-long crisis.

As a Ukrainian military helicopter exchanged fire with separatist militants along an airport highway in Donetsk and the thunder of mortar shells sent residents running for cover, Petro Poroshenko told reporters that he would move quickly to bring peace and stability to the country and that he planned to visit the violence-plagued Donets Basin in his first trip as Ukraine’s leader.

The parallel realities underscored the depth of Poroshenko’s challenges. Without the main airport of the Donets Basin, Ukraine’s industrial heartland, under full government control, even the basic practicality of fulfilling his pledge to visit was in question.

Poroshenko faces the daunting task of quelling the pro-Russian rebellion in the east while meeting the demands of the European-leaning constituency that elected him — tamping down corruption and modernizing the former Soviet republic’s economy. Whether the billionaire can successfully navigate Ukraine’s turbulent relationship with Russia will also be key.

Poroshenko, 48, a chocolate magnate who ran on a platform of bringing Ukraine closer to its European neighbors, vowed Monday to launch a swift military operation to crush the separatists, whom he likened to “Somali pirates.”

“Their goal is to turn Donbas into Somalia, and I will never allow such things to happen in my country,” he said, using another name for the Donets Basin and apparently citing the African nation as an example of a place where militants have more power than the state.

But he offered an olive branch to eastern Ukraine by saying that elections should take place to give residents there a measure of local control. And he conceded that the cooperation of Russia — which Kiev and the West have accused of fomenting the separatist rebellion — would be crucial to ending the violence.

“Russia is our biggest neighbor,” Poroshenko said. “Stopping war and bringing peace to all Ukraine, bringing stability to the eastern part of Ukraine, that will be impossible without the participation of Russia.”

Poroshenko said those talks would start as early as next month, adding that he and Russian President Vladimir Putin “know each other quite well.”

Russian officials said Monday that the Kremlin was ready to hold talks with Poroshenko, signaling a more conciliatory tone after months of finger-pointing between Kiev and Moscow amid a conflict that has left Russia’s relationship with the United States and Europe at its lowest point since the Cold War.

Russian Foreign Minister Sergei Lavrov said that Ukraine’s election Sunday was “not without problems.” But Russia will “respect the will expressed by the Ukrainian people,” he told reporters in Moscow, according to Russia’s Interfax news agency.

“We, as our president said repeatedly, are ready for a dialogue with Kiev representatives, ready for a dialogue with Petro Poroshenko,” Lavrov said.

Battle for the airport

The intense clash at the Donetsk airport, which continued Monday night, seemed to show a hardening of wills from the government and the rebels. The separatists — who have felt their cause jeopardized by internal divisions, waning support from Moscow and a decision by industrial magnate Rinat Akhmetov to throw his financial might to the side of unity — had declared martial law and demanded that Ukrainian troops leave.

The rebels seized the airport sometime before 7 a.m., when the airport’s Web site announced its closure and the cancellation of flights without an explanation. But the Ukrainian military showed its resolve to take the fight to the militants. Shortly after 1 p.m., four Ukrainian helicopters flew over the treetops near the airport, and within minutes, machine-gun fire erupted west of the terminal.

Explosions resounded along a major highway for hours, as armed rebels in fatigues and balaclavas darted through nearby woods. The helicopters opened fire on the rebels, and military jets zoomed low to drop chaff — bits of aluminum or small flares that military aircraft expel to confuse heat-seeking or radar-guided missiles — over the forest and highway.

A helicopter gunship destroyed a rebel-held antiaircraft array that was being used against Ukrainian security forces, said Vladislav Seleznev, a spokesman for the military’s anti-separatist operations.

Shots continued to ring out well after sundown, and it was unclear Monday night who was in control of the airport or how many people had been injured or killed in the fighting.

Observers say vote was fair

Poroshenko, a seasoned politician, captured 54 percent of Sunday’s presidential vote in an election that attracted a 60 percent turnout across the country, according to the Central Election Commission. In the Donetsk region, turnout was 15 percent, and in the eastern region of Luhansk it was 39 percent.

International observers said the elections were fair and well-organized, despite the voting problems in those eastern regions.

“The disenfranchisement in these places of voters represents a serious violation of rights. At the same time, it does not negate the legitimacy of the election,” said former U.S. secretary of state Madeleine Albright, who led a delegation of observers from the National Democratic Institute.

Still, some U.S. politicians who were in Kiev to monitor the elections said Russia disrupted the vote in the east — an action that the Obama administration previously said would trigger further sanctions against Russia.

“If there are other sanctions bills that come on the floor of the House, yeah, absolutely, I’m going to evaluate those with likely a very positive or favorable light,” said Rep. Michael C. Burgess (R-Tex.), who was in Kiev to observe the voting.

The election will give Ukraine’s leader a stronger negotiating position after months when an interim government, which took office after the ouster of pro-Russian president Viktor Yanukovych, had no popular mandate. And Poroshenko, who has worked as a cabinet minister in both pro-Kremlin and pro-Western governments, is considered well-placed to navigate between the two camps.

Poroshenko allied himself with Ukraine’s protest movement shortly after Yanukovych rejected a trade deal in November that would have moved Ukraine toward integration with the European Union. Yanukovych fled to Russia in February.

Russia has appeared to swing its support from the separatists to the new government in Kiev in recent days. But the Kremlin may not have any more intention now than it did several months ago of seeing Kiev slip out of its sphere of influence and into Europe’s. Continued chaos in the east may serve Russia’s interests by discouraging Ukraine’s prospects for E.U. membership.

“It’s not the end of the game,” said Fyodor Lukyanov, a Moscow-based political analyst and the editor in chief of Russia in Global Affairs magazine. “I think Putin’s view on Ukraine is that it is a very long-term crisis,” he said. And Poroshenko “will need to seek deals with Russia and the eastern part of the country.”

Adding to the challenge, the Kremlin’s intentions may be inherently at odds with Poroshenko’s goals, one analyst said.

“I think Russia’s strategy in the Ukrainian crisis is related to its fundamental desire to prevent Ukraine from joining the European Union and NATO in any kind of way,” said Grigory Golosov, a political science professor at St. Petersburg European University.

Ukrainians who voted for Poroshenko in more stable regions of the country expressed hope over the weekend that his experience — and the lesser nature of his corruption, compared with that of his peers — would give him an edge in resolving the nation’s conflict.

Buoyed by the election’s success, Kiev mayor-elect Vitali Klitschko said Monday that it was time to clear the city’s central square of the barricades and protester encampments that have blocked roads in and out of the area since November.

The presence of the encampments has been a goad to separatists who seized government buildings and set up barricades in eastern Ukraine; they accuse Kiev of enforcing a double standard.