KYIV, May 16 - The regiment that doggedly defended a steel mill as Ukraine’s last stronghold in the port city of Mariupol declared its mission complete Monday after more than 260 fighters, including some badly wounded, were evacuated and taken to areas under Russia’s control.

President Volodymyr Zelenskyy said the evacuation to separatist-controlled territory was done to save the lives of the fighters who endured weeks of Russian assaults in the maze of underground passages below the hulking Azovstal steelworks. He said the “heavily wounded” were getting medical help, The Associated Press reported.

Ukraine needs Ukrainian heroes to be alive. It’s our principle,” he said. An unknown number of fighters stayed behind to await other rescue efforts.

The steel mill’s defenders got out as Moscow suffered another diplomatic setback in its war with Ukraine, with Sweden joining Finland in deciding to seek NATO membership. And Ukraine made a symbolic gain when its forces reportedly pushed Russian troops back to the Russian border in the Kharkiv region.

Still, Russian forces pounded targets in the industrial heartland of eastern Ukraine known as the Donbas, and the death toll, already many thousands, kept climbing with the war set to enter its 12th week on Wednesday.

Deputy Defense Minister Hanna Maliar said 53 seriously wounded fighters were taken from the Azovstal plant to a hospital in Novoazovsk, east of Mariupol. An additional 211 fighters were evacuated to Olenivka through a humanitarian corridor.

She said an exchange would be worked out for their return home. Officials also planned to keep trying to save the fighters who remained inside.

The work to bring the guys home continues, and it requires delicacy and time,” Zelensky said.

Before Monday’s evacuations from the steelworks began, the Russian Defense Ministry announced an agreement for the wounded to leave the mill for treatment in a town held by pro-Moscow separatists. There was no immediate word on whether the wounded would be considered prisoners of war.

After nightfall Monday, several buses pulled away from the steel mill accompanied by Russian military vehicles. Maliar later confirmed that the evacuation had taken place.

Thanks to the defenders of Mariupol, Ukraine gained critically important time to form reserves and regroup forces and receive help from partners,” she said. “And they fulfilled all their tasks. But it is impossible to unblock Azovstal by military means.”

The commander of the Azov Regiment, which led the defense of the plant, said in a prerecorded video message released Monday that the evacuation marked the end of the regiment’s mission.

Absolutely safe plans and operations don’t exist during war,” Lt. Col. Denis Prokopenko said, adding that all risks were considered and part of the plan included saving “as many lives of personnel as possible.” (ap/ez)