WASHINGTON, March 4, 2023 (BSS/AFP) - The United States responded Friday to a Russian warning against arming Ukraine by offering a further $400 million in security assistance, as President Joe Biden hosted German Chancellor Olaf Scholz in a show of unity against Moscow.

The head of Russia's Wagner mercenary group meanwhile said its forces had "practically encircled" the eastern Ukraine city of Bakhmut, which has seen the fiercest fighting of Moscow's invasion.

Western military aid for Ukraine has been key to Kyiv's ability to hold out against Moscow's military onslaught and to even regain ground, but the Kremlin said such assistance will only "prolong the conflict and have sad consequences for the Ukrainian people."

Arms deliveries "place a significant burden on the economies of these countries and negatively affect the well-being of citizens of these countries, including Germany," Kremlin spokesman Dmitry Peskov said.

Washington ignored that warning, announcing the new security package for Kyiv that featured ammunition, including for the Himars precision rocket system that Ukrainian forces have used to devastating effect against Russian troops and supply dumps.

In a display of partnership after friction over supplying tanks to Ukraine, Biden hosted Scholz at the White House for first trip to Washington since Russia's invasion.

When they last met, "Russia was amassing its troops" on the border, Biden said in brief remarks to the press, adding the West had vowed to respond and "together we made good on that promise."

In reply, Scholz said it was important to send a message to Ukraine that "we will continue to (support it) as long as it takes and as long as it necessary."

The absence of a joint press conference raised questions about remaining difficulties, but the two leaders tried to dispel that impression, and Scholz said the bilateral relationship was "in a very good shape."

In another show of support for Ukraine, US Attorney General Merrick Garland made a surprise visit to the country on Friday to attend a conference on justice and war crimes.

"The attorney general held several meetings and reaffirmed our determination to hold Russia accountable for crimes committed in its unjust and unprovoked invasion against its sovereign neighbor," a Justice Department official said.

- Battle for Bakhmut -

Wagner chief Yevgeny Prigozhin said in a video released on Telegram Friday that the group's units "have practically surrounded Bakhmut, only one road remains" to be captured.

The 61-year old has regularly posted about advances of Wagner, his once-shadowy force that has taken center stage in the fight in eastern Ukraine.

He has said in recent weeks that his fighters have seized three villages north of Bakhmut -- Yagidne, Berkhivka and Paraskoviivka.

Ukraine has said it will defend "fortress Bakhmut" for as long as possible, but this week officials said the situation was difficult.

Russia is determined to seize Bakhmut -- a now-destroyed city once known for its sparkling wine -- as part of its wider aim of capturing the entire Donetsk region.

Ukrainian troops have held out for months, fighting brutal trench warfare and artillery battles that have flattened large portions of the city, and President Volodymyr Zelensky this week said that the fighting was "only increasing."

His comments followed an assessment from the commander of Ukraine's ground forces Oleksandr Syrskyi, who said it was "extremely tense" in the city.

- 'Measures' at border -

Both Ukrainian and Russian forces have reported heavy casualties in the struggle for control of Bakhmut, whose symbolic importance outstrips its military significance.

The battle has also exposed political rivalries between Prigozhin and Russia's regular army.

Last week, he issued an unprecedented call to Russians to take his side and urged the defense ministry to share ammunition with his fighters.
 
While the hotspot of the fighting is in the east of Ukraine, Russia said this week that a group of Ukrainian combatants had crossed into the southern Bryansk region.

Kyiv dismissed the claims as a "deliberate provocation."

Moscow says its regions bordering Ukraine are routinely shelled by Ukrainian forces, but the reported incursion was a rare instance of fighting inside Russia.

The Kremlin said Friday it would take steps to prevent cross-border incursions which killed two.

"Measures will be taken to prevent similar events in the future," Kremlin spokesman Peskov said.