Ukrainian President Volodymyr Zelenskyy is set to travel to Japan to attend the G7 summit in person, a top Ukrainian official said Friday.

Oleksiy Danilov, secretary of the National Security and Defence Council, told state television that "important" decisions would be made and it was "therefore the presence of our president that is absolutely essential in order to defend our interests."

The move had initially been reported by Bloomberg, Reuters news agency and the Financial Times.

The reported last-minute appearance has not been formally announced by Zelenskyy's office, although it has been speculated. Zelenskyy was initially expected to address the summit by video link.

On Thursday, Ukrainian government official Ihor Dzhokova told the Japanese news agency Kyodo that Zelenskyy would "carefully monitor the situation on the battlefield and then make a final decision" on whether or not he would attend in person.

He joins the leaders of a host of other countries, including Australia, Brazil, India, Indonesia and South Korea, who had been invited to join the G7 leaders in Hiroshima.

Here are some of the other notable developments concerning Russia's war in Ukraine on Friday, May 19:

Fresh sanctions against Russia expected at G7

US and UK announcements of fresh sanctions against Moscow started rolling early Friday, as the Group of Seven (G7) leaders' summit kicked off in Japan.

The British government said Prime Minister Rishi Sunak would announce a ban on Russian diamonds and imports of metals from Russia, including copper, aluminum and nickel.

The G7 as a whole is expected to further tighten existing sanctions against Russia over its war in Ukraine and announce restrictions on the multi-billion dollar export of rough diamonds from Russia.

Separately, multiple media outlets quoted a senior US government official as saying that Washington is slapping a new package of sanctions.

The US measures include cutting off about 70 companies from Russia and other countries from US exports, according to the unnamed official, who added that 300 sanctions against individuals, entities, vessels and aircraft would be announced.

Pentagon overestimated value of military aid to Ukraine

A US Defense Department spokesperson has acknowledged that the Pentagon overestimated the value of the weapons it had sent to Ukraine by at least $3 billion.

The accounting error could mean that the department is able to send more weapons to Ukraine without asking Congress for more money.

This comes as lawmakers are pressuring the Pentagon to show accountability for the billions of dollars it has sent in military aid.

"During our regular oversight process of presidential drawdown packages, the department discovered inconsistencies in equipment valuation for Ukraine," said Pentagon spokeswoman Sabrina Singh.

"In some cases, 'replacement cost' rather than 'net book value' was used, therefore overestimating the value of the equipment drawn down from US stocks," she added.

Singh stressed that the error had not hampered Washington's ability to send aid to the battlefield.

The additional support could be critical for Ukraine. Ukrainian President Volodymyr Zelenskyy has previously said that a widely anticipated counteroffensive was delayed because the military did not yet have everything it needed.

Air raid alerts declared across Ukraine

Air raid sirens sounded across Ukraine early Friday, and some regions reported explosions.

Officials said anti-aircraft units were in action in several regions. A day earlier, the Ukrainian military weathered what it said was an "unprecedented" air attack by Russia.

The military warned that there was a threat of strikes from hypersonic Kinzhal missiles to all regions of Ukraine.

Prigozhin says Bakhmut 'unlikely' to fall soon; Zelenskyy hails troops

Yevgeny Prigozhin, the head of the Russian Wagner mercenary group, said the eastern Ukrainian city of Bakhmut was "unlikely" to fall to Russian forces in the coming days.

"Bakhmut is unlikely to be completely taken tomorrow or the day after tomorrow," Prigozhin wrote on Telegram early Friday.

Prigozhin added that heavy fighting was ongoing in the southwestern suburbs of the city, which has seen the most protracted battle since Russia's war in Ukraine began on February 24, 2022.

"Bakhmut has not yet been taken. There is a suburb called 'samolet.' It is an impregnable fortress formed from a range of apartment blocks, located in the southwest of Bakhmut. The toughest battles are going on there right now."

The Wagner chief has repeatedly accused Moscow of not giving his forces enough ammunition to capture the city, which he had said his mercenaries would capture by May 9. Russia has been adamant about claiming victory there after several setbacks in the war.

Prigozhin's remarks came after Ukrainian and Russian officials said Kyiv's troops had gained up to 1 kilometer near Bakhmut.

Meanwhile, Ukrainian President Volodymyr Zelensky praised his soldiers during his regular nightly address.

"Firstly, the defensive brigades have done a good job, they have fulfilled the most important strategic tasks," he said in his evening video address. "And the offensive brigades are doing a good job."

Zelenskyy, however, refrained from giving any details about the combat operations and further steps.

More DW coverage on Russia's war in Ukraine

The Ukrainian city of Nikopol, near the occupied Zaporizhzhia nuclear power plant, has come under repeated bombardment from Russian troops stationed in Enerhodar. Residents speak to DW about their everyday life during wartime.