Ukraine continues to take back territory from Russia but Moscow says it will regain it.
The situation in four regions annexed by Russia will be stabilised, Vladimir Putin has vowed.
The Russian president announced the annexation of Luhansk, Donetsk, Zaporizhzhia and Kherson last week after self-proclaimed referendums, not recognised internationally.
But Ukraine says it has regained six villages in Luhansk.
It controls significant parts of the other three regions and has made more gains in Donetsk and Kherson recently.
However, Kremlin spokesman Dmitry Peskov said Russia would re-take any territory that had been lost.
Facing questions over the recent losses, he told reporters: “There is no contradiction here. They will be with Russia forever, they will be returned.”
In a speech to teachers on Russian teachers’ day, Mr Putin said he would “calmly develop” the annexed territories.
But Andrey Kartopolov, the chairman of the State Duma defence committee, told state media that Russia needed to stop lying about what was going on on the battlefield, saying that Russians were not stupid.
Ukrainian forces are making gains in both the south and the east.
Serhiy Haidai, Ukrainian governor of Luhansk, told the BBC on Wednesday that six villages in the region had been recaptured.
It comes after a series of gains in the southern region of Kherson the previous day, including the strategically key village of Davydiv Brid.
Russia is still working to mobilise reservists, after Mr Putin announced a call-up last month of 300,000 people who had completed compulsory military service.
But Mr Putin has rowed back on which groups will be affected, after strong opposition and protests in Russia against the move.
He has signed a decree exempting several categories of students, including first-time students at accredited institutions, and certain types of postgraduate students – such as those in the field of science.
Meanwhile, Rafael Grossi, the head of UN nuclear watchdog the International Atomic Energy Agency (IAEA), is on his way to Kyiv.
Mr Grossi wrote on Twitter that he was travelling for “important meetings” on the need for a protection zone around the Zaporizhzhia nuclear plant.
The plant, near the front line, has been under Russian control since March. Reports of fighting around it have sparked international concern, and the last of its reactors was shut down last month.
The IAEA, which has two experts onsite, is preparing to restart one of the reactors at reduced power to provide heat for the plant.
Earlier, Mr Putin signed a decree saying that the Russian government would integrate the plant’s nuclear facilities as Russian property.
But the head of Ukrainian nuclear operator Enerhoatom, Petro Kotin, said that all decisions about the plant’s operation will be taken in the company’s central office in Kyiv.
“We will continue to work in accordance with Ukrainian legislation within the Ukrainian energy system, in Enerhoatom,” he is quoted by the Interfax-Ukraine news agency as saying.