Russia-Ukraine updates: 2 US veterans who joined Ukrainian forces missing

The war in Ukraine is taking a toll on Russia's military, the U.K. Ministry of Defense said Saturday.

"The conflict in Ukraine is taking a heavy toll on some of Russia’s most capable units and most advanced capabilities. It will take considerable time and expense for Russia to reconstitute its armed forces following this conflict," the ministry said in a statement.

Adding, "It will be particularly challenging to replace modernized and advanced equipment due to sanctions restricting Russia’s access to critical microelectronic components."

At least one T-90M, Russia's newest tank, with its strongest armor, has been destroyed in the fighting, the Ministry of Defense said.

The Russian military has approximately 100 T-90M tanks currently in service, including those in Ukraine, but the system's upgraded armor "remains vulnerable if unsupported by other elements," the defense ministry said.

First Lady Jill Biden kicked off the first day of her overseas trip by visiting Mihail Kogalniceanu Air Base in Romania, where she met with U.S. troops and NATO military leadership.

The U.S. deployed troops to the base, which is about 60 miles from the border with Ukraine, in the leadup to Russia's invasion of Ukraine.

Prior to departing the U.S. last night, the first lady told reporters, "It was so important to the president and to me that the Ukrainian people know that we stand with them."

Biden drew cheers Friday when she greeted soldiers with a bottle of ketchup in hand -- a commodity that has been in short supply on the base, according to her spokesperson.

Wearing a Beau Biden Foundation hat, the first lady helped serve mac and cheese and potatoes and shook hands and took photos with the service members. She also participated in a special story-time with United Through Reading, an organization that connects military families with a deployed service member through video recordings and virtual book readings.

Biden also met with members of the Delaware National Guard before departing the base for Bucharest.

-ABC News' Allison Pecorin and Molly Nagle

The U.S. has announced another package of security assistance that will provide "additional artillery munitions, radars, and other equipment to Ukraine," according to a Friday afternoon statement from President Joe Biden.

The U.S. will provide up to $150 million in new security assistance for Ukraine, according to a memorandum from Biden.

"With today’s announcement, my Administration has nearly exhausted funding that can be used to send security assistance through drawdown authorities for Ukraine," Biden said in the statement. "For Ukraine to succeed in this next phase of war its international partners, including the U.S., must continue to demonstrate our unity and our resolve to keep the weapons and ammunition flowing to Ukraine, without interruption. Congress should quickly provide the requested funding to strengthen Ukraine on the battlefield and at the negotiating table."

The package includes 25,000 155mm artillery rounds, counter-artillery radars, electronic jamming equipment, field equipment and spare parts, according to Pentagon spokesperson John Kirby.

"Capabilities in this package are tailored to meet critical Ukrainian needs for today's fight as Russian forces continue their offensive in eastern Ukraine," Kirby said in a statement.

This marks the ninth drawdown of equipment from Department of Defense inventories for Ukraine since August 2021, according to Kirby.

-ABC News' Molly Nagle

The United Nations Security Council has unanimously adopted a statement voicing "deep concern regarding the maintenance of peace and security of Ukraine," the first such message issued by the body since the war began.

The statement reminds all U.N. members of their responsibility to “settle their international disputes by peaceful means” and express “support of the efforts of the Secretary-General in the search for a peaceful solution.”

The text was drafted by envoys from Norway and Mexico and was agreed upon by all members of the council, including Russia.

The permanent representative from Mexico, Juan Ramón de la Fuente, said it demonstrated all members of the Security Council were “united” in the pursuit of “diplomatic resolution,” although he acknowledged it took over two months to reach this point.

Pressed on whether he thought Russia was earnestly seeking a peaceful end to the war, Ramón de la Fuente said the country demonstrated “a willingness to move in that direction.”

However, the UNSC’s statement is already drawing criticism from those who say it fails to hold Russia accountable for the violence.

U.N. Secretary-General António Guterres said in a statement: "I welcome this support and will continue to spare no effort to save lives, reduce suffering and find the path of peace."

-ABC News' Shannon Crawford