The Patriot missile training for Ukrainian troops at Fort Sill, Oklahoma, is wrapping up soon, an Army spokesman said Tuesday.

Sixty-five Ukrainian soldiers have been training at Fort Sill since mid-January in an expedited training cycle on using the Patriots -- training that typically can last up to a year.

The Ukrainians will depart the Army post in the coming days for Europe, where they will receive additional training, before heading back to Ukraine "in the coming weeks," Col. Marty O’Donnell of U.S. Army Europe/Africa told ABC News.

"In Europe, the Ukrainians training here will meet up with Ukrainians training in Europe, and with U.S., German, and Dutch equipment donations to validate the systems and ensure interoperability," O'Donnell said.

-ABC News' Luis Martinez

The United States is going to speed up the manufacture and delivery of the 31 Abrams tanks President Joe Biden approved sending to Ukraine, a U.S. official confirmed Tuesday.

Instead of making new tanks from scratch, the Department of Defense will now refurbish the hulls of several older models that will be equipped with more modern equipment, according to the official.

The new delivery target date is fall 2023, the official said; previously the anticipated delivery time was believed to be mid-2024.

National Security Council spokesperson John Kirby hinted at the accelerated timeline on Tuesday.

"We're working on that," Kirby said on MSNBC. "There's some changes that you can make to the process to sort of speed that up."

-ABC News' Luis Martinez and Teresa Mettela

Japanese Prime Minister Fumio Kishida visited Ukraine on Tuesday for the first time since the start of Russia's invasion.

In Kyiv, Kishida laid a wreath at the memorial for fallen Ukrainian soldiers. In Bucha, where Ukrainian officials said more than 400 civilians were killed last year by Russian forces, he laid a wreath outside a church before observing a moment of silence and bowing.

"The world was astonished to see innocent civilians in Bucha killed one year ago," Kishida said. "I really feel great anger for all the atrocious acts."

-ABC News' Ellie Kaufman

Ukrainian forces destroyed Russian Kalibr-NK cruise missiles in a drone strike in Crimea as the weapons were being transported by rail, the Ukrainian Main Intelligence Directorate said on their official Telegram channel Monday.

Sergey Aksyonov, an adviser to the head of the Republic of Crimea, which Russia annexed in 2014, confirmed a drone attack on his official Telegram channel.

Debris from the aerial object damaged a household and a shop and one person was injured from the explosions, Aksyonov said.

-ABC News' Ellie Kaufman

The Russian oligarch behind the Wagner private paramilitary group fighting for the Kremlin in Ukraine is threatening a mutiny if his forces are not resupplied with ammunition soon.

Yevgeny Prigozhin, owner and curator of the Wagner group, penned a letter to Russian Defense Minister Sergei Shoigue, demanding ammunition be provided to his forces on the battlefield.

In the letter, Prigozhin wrote that if supply problems are not fixed fast, he will complain to Russian President Vladimir Putin and his mercenaries would abandon their positions in Bakhmut, Ukraine, where heavy fighting has been going on for weeks, The Moscow Times reported.

“I appeal to Shoigu with a request to immediately issue ammunition. In case of refusal, I consider it necessary to convey to the Supreme Commander-in-Chief information about the existing problem in order to make a decision and about the advisability of further presence of Wagner PMC in Bakhmut in the conditions of a shortage of ammunition," Prigozhin wrote.

He added, "If the deficit is not replenished ... we will be forced to withdraw part of the units from this territory, and then everything else will crumble. Therefore, the bell is already ringing -- it is called an alarm."

Emphasizing the urgency, Prigozhin noted that Ukraine is planning to launch a counteroffensive soon.

There was no immediate public response from Shoigu or the Kremlin.

"We need to stop deceiving the population and telling that everything is fine with us," Prigozhin wrote. "I must honestly say: Russia is on the brink of disaster. If these screws are not adjusted today, the 'aircraft' will crumble in the air."