By OLEK­SAN­DR STA­SHEVSKYI and DAVID KEY­TON-As­so­ci­at­ed Press

KYIV, Ukraine (AP) — Russ­ian troops are with­draw­ing from around Ukraine’s sec­ond-largest city af­ter bom­bard­ing it for weeks, the Ukrain­ian mil­i­tary said Sat­ur­day, as Kyiv and Moscow’s forces en­gaged in a grind­ing bat­tle for the coun­try’s east­ern in­dus­tri­al heart­land.

Ukraine’s gen­er­al staff said the Rus­sians were pulling back from the north­east­ern city of Kharkiv and fo­cus­ing on guard­ing sup­ply routes, while launch­ing mor­tar, ar­tillery and airstrikes in the east­ern Donet­sk province in or­der to “de­plete Ukrain­ian forces and de­stroy for­ti­fi­ca­tions.”

De­fense Min­is­ter Olek­sii Reznikov said Ukraine was “en­ter­ing a new - long-term - phase of the war.”

Pres­i­dent Volodymyr Ze­len­skyy said Ukraini­ans were do­ing their “max­i­mum” to dri­ve out the in­vaders and that the out­come of the war would de­pend on sup­port from Eu­rope and oth­er al­lies.

“No one to­day can pre­dict how long this war will last,” Ze­len­skyy said in his night­ly video ad­dress late Fri­day.

In a show of sup­port, a U.S. Sen­ate del­e­ga­tion led by Re­pub­li­can leader Mitch Mc­Connell met with the Ukrain­ian pres­i­dent Sat­ur­day in Kyiv. A video post­ed on Ze­len­skyy’s Telegram ac­count showed Mc­Connell, who rep­re­sents the state of Ken­tucky, and fel­low Re­pub­li­can sen­a­tors Su­san Collins of Maine, John Bar­ras­so of Wyoming and John Cornyn of Texas greet­ing him.

Their trip came af­ter Ken­tucky’s oth­er sen­a­tor, Rand Paul, blocked un­til next week the Sen­ate’s ap­proval of an ad­di­tion­al $40 bil­lion to help Ukraine and its al­lies with­stand Rus­sia’s three-month old in­va­sion.

Af­ter Russ­ian forces failed to cap­ture Kyiv fol­low­ing the Feb. 24 in­va­sion, Pres­i­dent Vladimir Putin shift­ed his fo­cus east­ward to the Don­bas, an in­dus­tri­al re­gion where Ukrain­ian troops have bat­tled Moscow-backed sep­a­ratists since 2014.

Rus­sia’s of­fen­sive aims to en­cir­cle Ukraine’s most ex­pe­ri­enced and best-equipped troops, who are based in the east, and to seize parts of the Don­bas that re­main in Ukraine’s con­trol.

Airstrikes and ar­tillery bar­rages make it ex­treme­ly dan­ger­ous for re­porters to move around in the east, hin­der­ing ef­forts to get a full pic­ture of the di­rec­tion the fight­ing is tak­ing. But the bat­tle ap­pears to be a back-and-forth slog with no ma­jor break­throughs on ei­ther side.

Rus­sia has cap­tured some Don­bas vil­lages and towns, in­clud­ing Ru­bizhne, a city with a pre­war pop­u­la­tion of around 55,000.

Ze­len­skyy said Ukraine’s forces have al­so made progress in the east, re­tak­ing six Ukrain­ian towns or vil­lages in the past day.

Kharkiv, which is not far from the Russ­ian bor­der and on­ly 80 kilo­me­ters (50 miles) south­west of the Russ­ian city of Bel­go­rod, has un­der­gone weeks of in­tense shelling. The large­ly Russ­ian-speak­ing city with a pre­war pop­u­la­tion of 1.4 mil­lion was a key Russ­ian mil­i­tary ob­jec­tive ear­li­er in the war, when Moscow hoped to cap­ture and hold ma­jor Ukrain­ian cities.

Ukraine “ap­pears to have won the Bat­tle of Kharkiv” the In­sti­tute for the Study of War, a Wash­ing­ton-based think tank, said. “Ukrain­ian forces pre­vent­ed Russ­ian troops from en­cir­cling, let alone seiz­ing Kharkiv, and then ex­pelled them from around the city, as they did to Russ­ian forces at­tempt­ing to seize Kyiv.”

Re­gion­al gov­er­nor Oleh Sinegubov said in a post on the Telegram mes­sag­ing app that there had been no shelling at­tacks on Kharkiv in the past day.

He added that Ukraine had launched a coun­terof­fen­sive near Izyum, a city 125 kilo­me­ters (78 miles) south of Kharkiv which was held by Rus­sia since at least the be­gin­ning of April.

Fight­ing was fierce on the Siver­sky Donets Riv­er near the city of Severodonet­sk, where Ukraine has launched coun­ter­at­tacks but failed to halt Rus­sia’s ad­vance, said Oleh Zh­danov, an in­de­pen­dent Ukrain­ian mil­i­tary an­a­lyst.

“The fate of a large por­tion of the Ukrain­ian army is be­ing de­cid­ed — there are about 40,000 Ukrain­ian sol­diers,” he said.

How­ev­er, Russ­ian forces suf­fered heavy loss­es in a Ukrain­ian at­tack that de­stroyed a pon­toon bridge they were us­ing to try to cross the same riv­er — the largest in east­ern Ukraine — in the town of Bilo­horiv­ka, Ukrain­ian and British of­fi­cials said. It was an­oth­er sign of Moscow’s strug­gle to sal­vage a war gone awry.

Britain’s De­fense Min­istry said Rus­sia lost “sig­nif­i­cant ar­mored ma­neu­ver el­e­ments” of at least one bat­tal­ion tac­ti­cal group in the at­tack. A Russ­ian bat­tal­ion tac­ti­cal group con­sists of about 1,000 troops.

The min­istry said the risky riv­er cross­ing was a sign of “the pres­sure the Russ­ian com­man­ders are un­der to make progress in their op­er­a­tions in east­ern Ukraine.”

Ze­len­skyy said in his night­ly video ad­dress that Ukraini­ans were do­ing every­thing they could to dri­ve out the Rus­sians and pushed for the West to in­crease its sup­port.

“This will de­pend, un­for­tu­nate­ly, not on­ly on our peo­ple, who are al­ready giv­ing their max­i­mum,” he said. “This will de­pend on our part­ners, on Eu­ro­pean coun­tries, on the en­tire free world.”

The Ukrain­ian leader warned that the war was caus­ing a food cri­sis around the world as a Russ­ian block­ade stops Ukrain­ian grain from leav­ing port.

The Group of Sev­en lead­ing economies echoed that warn­ing, say­ing Sat­ur­day that “Rus­sia’s war of ag­gres­sion has gen­er­at­ed one of the most se­vere food and en­er­gy crises in re­cent his­to­ry, which now threat­ens those most vul­ner­a­ble across the globe.”

Putin launched the war in Ukraine aim­ing to thwart NA­TO’s ex­pan­sion in East­ern Eu­rope. But the in­va­sion of Ukraine has oth­er coun­tries along Rus­sia’s flank wor­ried they could be next.

This week, the pres­i­dent and prime min­is­ter of Fin­land said they fa­vored their coun­try seek­ing NA­TO mem­ber­ship. Of­fi­cials in Swe­den are ex­pect­ed to an­nounce a de­ci­sion Sun­day on whether to ap­ply to join the West­ern mil­i­tary al­liance.

Putin told Finnish Pres­i­dent Sauli Ni­in­is­to that there are no threats to Fin­land’s se­cu­ri­ty and join­ing NA­TO would be an “er­ror” that would “neg­a­tive­ly af­fect Russ­ian-Finnish re­la­tions.”

The Krem­lin said the two lead­ers had a “frank ex­change of views” in a phone call on Sat­ur­day.

Ni­in­istö said the dis­cus­sion “was straight­for­ward and un­am­bigu­ous and was held with­out ex­ag­ger­a­tion. Avoid­ing ten­sions was con­sid­ered im­por­tant.”

Rus­sia’s re­sponse to the moves by Fin­land and Swe­den has so far been mut­ed, though Deputy For­eign Min­is­ter Alexan­der Grushko said Sat­ur­day that their ac­ces­sion to NA­TO would height­en se­cu­ri­ty ten­sions in the Arc­tic, “turn­ing it in­to an are­na of mil­i­tary com­pe­ti­tion.”

The Nordic na­tions’ po­ten­tial bids were thrown in­to ques­tion Fri­day when Turk­ish Pres­i­dent Re­cep Tayyip Er­do­gan said his coun­try is “not of a fa­vor­able opin­ion” to­ward the idea.

U.S. Sec­re­tary of State Antony Blinken is sched­uled to meet his NA­TO coun­ter­parts, in­clud­ing the Turk­ish for­eign min­is­ter, this week­end in Ger­many.

In oth­er de­vel­op­ments:

— Ukrain­ian fight­ers holed up in a steel plant in the ru­ined south­ern port of Mar­i­upol faced con­tin­ued Russ­ian at­tacks on the last strong­hold of re­sis­tance in the city. Ukraine’s deputy prime min­is­ter said Ukrain­ian au­thor­i­ties are ne­go­ti­at­ing the evac­u­a­tion of 60 se­vere­ly wound­ed troops from the steel­works. Iry­na Vereshchuk said Rus­sia had not agreed to the evac­u­a­tion of all wound­ed fight­ers at the plant, who num­ber in the hun­dreds.

The deputy speak­er of the Russ­ian par­lia­ment, An­na Kuznetso­va, vis­it­ed Kher­son, a re­gion bor­der­ing the Black Sea that has been held by Rus­sia since the ear­ly days of the war. Rus­sia has in­stalled a pro-Moscow re­gion­al ad­min­is­tra­tion, and Britain’s de­fense min­istry said Rus­sia could stage a lo­cal ref­er­en­dum on join­ing Rus­sia, with the re­sults like­ly ma­nip­u­lat­ed to show ma­jor­i­ty sup­port for break­ing away from Ukraine.

Yesi­ca Fisch in Bakhmut, Yuras Kar­manau in Lviv, Mstyslav Cher­nov in Kharkiv, Ele­na Be­ca­toros in Ode­sa, Jill Law­less in Lon­don and oth­er AP staffers around the world con­tributed to this re­port.