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

As Russia's stock of modern high-precision missiles depletes, its invading forces are turning to obsolete Soviet models to strike targets in Ukraine, Yuriy Ignat, spokesperson for the Ukrainian Air Force, said at a press briefing on Tuesday.

"Recently, there has been a tendency for Russia to save high-precision, expensive missiles. And now the enemy is increasingly using Soviet types of missiles,” Ignat said.

Some of these missiles are extremely powerful, the spokesman added, and their destructive parts can weigh up to 900 kilograms.

“Their main drawback is that they do not always fly at their intended target and very often destroy civilian objects with human casualties.”

According to Ignat, Ukrainian anti-aircraft missile forces have shot down more than 500 enemy air targets since the start of the full-scale Russian invasion. These include Russian cruise missiles, UAVs, planes and helicopters.

Arnold Schwarzenegger, the former Governor of California, weighed in on the question of Russian missiles on Tuesday when he said that Europe is partly to blame for financing Russia's war against Ukraine.

Addressing a climate conference in Vienna via a livestream, Schwarzenegger said the about 1,300 missiles Russia fired into Ukrainian cities during the first two months of the war cost 7.7 billion euros.

“Now that’s a lot. But during the same time, Europe sent to Russia 44 billion euros for fuel,” the former governor told attendees of the Austrian World Summit. “We have blood on our hands, because we are financing the war. We have to stop lying to ourselves.”

On the other end of the frontline, Ukraine is also grappling with a pressing lack of weapons. The Ukrainian forces received only 10% of the weapons “we said we needed,” Ukrainian Deputy Defense Minister Hanna Malyar told local media on Tuesday.

“Now matter how much effort Ukraine makes, we will not be able to win the war without the help of the West,” Malyar added.

The deputy minister said Ukrainian fighters can afford to spend only about 6,000 shells a day, while the Russians use about ten times more. The limited number of available weapons and ammunition is crippling Ukraine's ability to launch a counteroffensive at the front, military expert Oleh Zhdanov said, according to local outlets.

Speaking at an online press conference for Danish media on Tuesday, Ukrainian President Volodymyr Zelenskyy repeated his plea for Western weapons that he said are vital for the liberation of occupied territories.

The speed of de-occupation “depends on the supply of weapons to Ukraine, and any delays in this matter threaten stagnation on the front,” Zelenskyy said.

Meanwhile, Russian President Vladimir Putin likely still wants to capture much if not all of Ukraine but has had to narrow his tactical objectives in war, Under Secretary of Defense for Policy Colin Kahl said on Tuesday, according to Reuters.

"I still think he has designs on a significant portion of Ukraine, if not the whole country. That said, I do not think he can achieve those objectives," Kahl said, speaking at an event hosted by the Center for New American Security.

-ABC News' Edward Szekeres, Nataliia Kushnir, Max Uzol and Yulia Drozd

Russian and Belarusian tennis players, who are banned from Wimbledon, will be allowed to compete in this year's U.S. Open, but only under a neutral flag, the U.S. Tennis Association said.

The USTA said it "previously condemned, and continues to condemn, the unprovoked and unjust invasion of Ukraine by Russia."

Russian player Daniil Medvedev, the current No. 1 player in the world, won last year's U.S. Open.

The only way to end the war in Ukraine, either on the battlefield or behind the negotiation table, is a parity of weapons, Mykhailo Podoliak, an adviser to the head of the Ukrainian Presidential Office, said on Monday.

“Being straightforward -- to end the war we need heavy weapons parity,” Podoliak said on Twitter.

According to the presidential adviser, Ukraine's military wish list includes 1,000 howitzers, 300 multiple launch rocket systems, 500 tanks, 2,000 armored vehicles and 1,000 drones.

“Negotiations are possible from a strong position, which requires parity of weapons,” Podoliak said. “There is simply no other way.”

Ukrainian Foreign Minister Dmytro Kuleba echoed Podoliak's plea for weapons on Monday in a tweet that recounted Ukraine's recent military triumphs achieved with limited resources.

“Ukraine has proven it can punch well above its weight and win important battles against all odds,” Kuleba said, pointing at victories in the battles of Kyiv, Chernihiv, Sumy and Kharkiv. “Imagine what Ukraine can do with sufficient tools,” the Foreign Minister added. Kuleba urged Ukraine's partners “to set a clear goal of Ukrainian victory and speed up deliveries of heavy weapons.”

Podoliak said a meeting of NATO defense ministers will be held in Brussels on June 15.

“We are waiting for a decision" on the weapons, Podoliak said.

The group, known as the Ukraine Defence Contact Group, will convene a meeting for the third time in a bid “to ensure that we're providing Ukraine what Ukraine needs right now,” U.S. Secretary of Defense Lloyd J. Austin III said at a press briefing in Bangkok, Thailand, on Monday.

Austin, who will be in attendance in Brussels, said that Ukraine needs support “in order to defend against Russia's unjustified and unprovoked assault.” The Secretary of Defense noted that looking ahead, Ukraine will require help “to build and sustain robust defenses so that it will be able to defend itself in the coming months and years.”

In his Monday evening address, Ukrainian President Volodymyr Zelenskyy called on Ukrainians to tell people in the occupied territories “that the Ukrainian army will definitely come.”

“Tell them about Ukraine. Tell them the truth. Say that there will be liberation,” the president said.

Meanwhile, Ukrainian officials played down threats of possible food shortages in the country due to the ongoing conflict. While Ukraine lost 25% of its sown area as a result of Russia' full-scale invasion, the country's food security was “in no way” threatened, Taras Vysotsky, the first deputy minister of Agrarian Policy, said at a press briefing for Ukrainian media on Monday.

“Despite the loss of 25% of sown areas, the structure of crops this year as a whole is more than sufficient to ensure consumption, which in turn also decreased due to mass displacement and external migration," Vysotsky said.

The deputy minister added that Ukraine has “already imported about 70% of essential fertilizers, 60% of plant protection products and about a third of the required amount of fuel” before the war erupted in late February. According to Vysotsky, current sowing volumes are enough to ensure domestic consumption and even exports.

-ABC News' Edward Szekeres, Yuriy Zaliznyak, Max Uzol and Yulia Drozd

Another mass grave has been dug up in Bucha, uncovering the bodies of seven men who authorities believe were tortured and killed during the bloody occupation of the city in March.

Police told ABC News their hands were tied with ropes behind their backs and they were shot in the knees and head.

"They were killed in a cruel way," police spokesperson Iryna Pryanyshnykova said. "These were civilian victims. The people here were killed by Russian soldiers and later they were just put into a grave to try to hide this war crime."

It's not clear why the men were killed, Pryanyshnykova said.

She said experts will analyze DNA to identify the victims.

-ABC News' Britt Clennett