Russian Foreign Minister Sergey Lavrov "diverted" U.S. Secretary of State Antony Blinken's calls to reconsider the decision to suspend Russia's participation in the New START treaty, Russia's foreign ministry told Interfax, Russian news agency.

“If they want to return to diplomacy, let them return. If they are engaged in self-promotion and such inexpensive PR, well, this is possible. True, the result will be appropriate," Maria Zakharova, a spokesperson for the ministry, told Russian TV channel Rossiya-1.

-ABC News' Natalia Shumskaia

U.S. Secretary of State Antony Blinken and Russian Foreign Minister Sergey Lavrov had an "on the go" talk during the G-20 Meeting of Foreign Ministers in India, but there were no negotiations, Russian Foreign Ministry spokeswoman Maria Zakharova told TASS, a Russian news agency, Thursday.

"Blinken asked for a contact with Lavrov. Sergey Viktorovich [Lavrov] had communication on the go during the second session. But there were no negotiations, no meeting or so on," the diplomat said.

Blinken had said earlier in the day during a press conference he had "spoke briefly" with Lavrov and discussed ending the war, as well as Russia rejoining the New START Treaty on nuclear arms.

"I told the foreign minister what I and so many others said last week at the United Nations and what so many G-20 foreign ministers said today: End this war of aggression, engage in meaningful diplomacy that could produce a just and durable peace," he said. "The United States stands ready to support Ukraine through diplomacy to end the war on this basis."

A senior State Department official downplayed any hopes that the conversation moved the needle on any of the topics.

-ABC News' Tanya Stukalova and Shannon Crawford

Ukraine has shot down 80% of Russian missiles, according to Commander of the Joint Forces of the Ukrainian Air Force Serhiy Nayev.

Nayev made the assessment in a Facebook post on Wednesday about the effectiveness of the air defense system.

"The enemy is also changing his tactics and ways of using air strike means, so we test after every hit," he wrote. "This analysis proves that commanders, respectively, make decisions that ensure the durability of the air defense is at the highest level."

-ABC News' Ellie Kaufman

Colonel-General Oleksandr Syrsky, the commander of Ukraine's Eastern Group of Forces, will send additional units to Bahkmut, according to Ukraine's Deputy Defense Minister Hanna Malyar.

"Bakhmut has been the epicenter of hostilities for several months now. The enemy has concentrated its key efforts there because it aims to reach the borders of the Donetsk region. The situation there is really tense and difficult," Malyar said.

Ukrainian President Volodymyr Zelenskyy echoed that statement in his nightly address.

"The most difficult situation is still Bakhmut and the battles that are important for the defense of the city," he said.

-ABC News' Ellie Kaufman and Will Gretsky

One year ago, with Ukraine's borders surrounded by what seemed to be a superior military force, many U.S. officials and analysts predicted a swift Russian blitz to Kyiv.

But after Russian President Vladimir Putin sent his more than 150,000 arrayed troops across the border, it soon became clear that a dual reassessment was in order: The Russian invaders were less potent than advertised, and the Ukrainians were unexpectedly stubborn and wily in the defense.

Some of the Russian troops weren’t even aware they were on a combat mission until Ukrainian bullets came cracking past them, according to U.S. officials. Meanwhile, Ukrainian forces stalled a massive Russian supply convoy through direct attacks and by destroying a key bridge. Only one week into the invasion, Putin's men were plagued with food and fuel shortages, morale running similarly low.

Kyiv stood.

"Putin assumed that Ukraine was an easy target, Putin assumed that Kyiv would easily fall, and Putin assumed that the world would stand by," U.S. Secretary of Defense Lloyd Austin said during a speech in Brussels last week. "But the Kremlin was wrong on every count."

Ukrainian forces were armed with more than grit.

They also had years of U.S. and NATO military training, plus American-made weapons, like anti-armor Javelins and anti-aircraft Stinger missiles. These made Russian vehicles vulnerable to ambush, and left Russian helicopter and jet pilots wary of flying over Ukrainian positions. Indeed, many airmen did not return from their sorties.

Despite astonishing losses of soldiers and vehicles, Putin has shown no inclination to end the conflict anytime soon. And despite its tenacity, Ukraine has also taken significant casualties, and is not able to produce enough of its own weapons and ammunition to keep up the fight.

Ukraine, after thwarting the advance on its capital, and later routing Russian forces from Kharkiv, now largely faces a battle of supply.

"When this war began, Russia had a larger population, a much bigger defense budget, a bigger military, bigger industrial base. So, this became an industrial war and a war of industrial bases," said Seth Jones, director of the International Security Program at the Center for Strategic and International Studies. "This is why Western industrial support has been so critical."

A key question now is, despite massive military aid packages and a promise to send even more, could the U.S. strategy ultimately result, not in a Ukrainian victory, but a stalemate in a years-long war of attrition?

-ABC News' Matt Seyler