DONETSK, Ukraine — The Ukrainian government vowed to push ahead Wednesday with military operations against pro-Russian separatists in the embattled east of the country after a big show of strength in routing rebels from this city’s international airport.

Petro Poroshenko, Ukraine’s president-elect, said the “anti-terrorist operation” against the rebels, whom he has likened to Somali pirates, “has finally really begun.”

Ukraine’s military on Tuesday used Soviet-era fighter jets and attack helicopters to pound rebels and retake Donetsk’s Sergei Prokofiev International Airport. The rebels, who said they suffered a heavy loss of life in the two-day operation, had seized the airport Monday, a day after Ukraine’s presidential and mayoral elections.

Exchanges of machine-gun fire and explosions continued near the airport Wednesday.

In eastern Ukraine, Donetsk Mayor Aleksandr Lukyanchenko said on his website that the city, capital of a region declared a sovereign republic by separatists after a chaotic referendum on self-rule, was “relatively calm” Wednesday morning. But in the town of Marinka, about 20 miles west of Donetsk, 11 monitors from the Organization for Security and Cooperation in Europe were detained by an unidentified armed group for about seven hours Wednesday, then released under unclear circumstances and escorted back to Donetsk.

Four other monitors are still missing after disappearing near Donetsk on Monday night.

Denis Pushilin, a leader of the so-called “Donetsk People’s Republic,” addressed a rally of a few hundred people in Donetsk’s Lenin Square on Wednesday, issuing a call to the region’s miners to join the separatist fight.

Pushilin said the rebels would continue to defy Ukrainian ultimatums to lay down their arms. He also said more volunteers – “our brothers” – were coming from friendly regions and states to Donetsk as reinforcements.