KYIV, June 14 - Russian forces fired cruise missiles at the southern Ukrainian city of Odesa and shelled the eastern Donetsk region early Wednesday, killing at least six people and damaging dozens of homes, regional Ukrainian officials said.

Russian forces have recently stepped up aerial strikes in their nearly 16-month war, a Ukrainian military spokesman said. The country’s armed forces, meanwhile, have reported limited gains in the early stages of a counteroffensive to take back the nearly one-fifth of Ukraine’s territory that is under Russian control.

The grinding Ukrainian advance is pressing slowly ahead, Deputy Defense Minister Hanna Maliar said Wednesday. Western analysts and military officials say the effort to dislodge entrenched, powerfully armed and large numbers of Russian troops could take years.

Ukrainian troops have advanced 200-500 meters (650-1,600 feet) at various sections of the front line around the Donetsk city of Bakhmut and 300-350 meters (980-1,150 feet) in the southern Zaporizhzhia region, Maliar claimed. Ukrainian forces have managed to make gains despite the Russian edge in artillery and air power and large number of landmines left behind by Russian troops, she said. Maliar noted that, since the start of Russia’s full-scale invasion, Ukraine’s losses on the battlefield had been “incomparably smaller” than those of Russian troops.

Ukrainian forces can expect to make slow progress in what will be a “hugely difficult” fight as the counteroffensive gains traction, a Western official said on condition of anonymity to discuss intelligence.

“Intense fighting is now ongoing in nearly all sectors of the front,” the official said. “This is much more than probing. These are full-scale movements of armor and heavy equipment into the Russian security zone.”

The official described the Ukrainian attacks as methodical and said that, broadly speaking, “Russian forces have put up a good defense.”

In Odesa, three food warehouse employees were killed in a strike that also damaged homes, shops and cafes in the city’s downtown, the regional administration said on Facebook. An additional 13 people were wounded.

Search teams were looking for possible survivors under the rubble of the warehouse, it said.

The attack on the port city, launched from the Black Sea, was the second in a week and involved four Kalibr cruise missiles, three of which were intercepted by air defenses, the administration said.

In eastern Ukraine, Donetsk province Gov. Pavlo Kyrylenko wrote on Telegram that at least three people died after shelling destroyed seven homes and damaged dozens of others in the cities of Kramatorsk and Kostiantynivka.

Ten towns and villages along the front line in Donetsk were struck as Kyiv’s troops slowly advance, according to Ukraine’s presidential office.

A missile hit the Ukrainian-controlled city of Kramatorsk, where Kyiv’s forces are headquartered, killing two civilians and wounding two others while damaging 29 homes, the presidential office said. Russian shelling of Kostiantynivka killed one civilian, with 57 houses damaged, it added.

Andriy Kovalov, a spokesperson for the General Staff of Ukraine’s armed forces, said the Russian military increased missile and aerial strikes as Kyiv’s forces intensify attacks along the war’s 1,000-kilometer (600-mile) front line and claim some modest gains at the beginning of their counteroffensive.

In a briefing, he said strikes on the Kharkiv, Donetsk and Kirovohrad regions, in addition to the Odesa region, involved Kh-22 cruise missiles, sea-launched Kalibr cruise missiles, and Iranian-made Shahed drones. Nine were intercepted. (ap/ez)