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

Russia’s Wagner mercenary group said it will retreat from Bakhmut because of severe shortages in ammunition, according to Yevgeny Prigozhin, the group's leader. He said his forces would withdraw on May 10, blaming Russia’s defense ministry for the retreat.

Wagner has played a crucial role for months in the fighting for Bakhmut, sustaining huge casualties. The announcement and the suggestion of bitter infighting within Russia’s military forces signals division and disorganization just as Russia is bracing for a major Ukrainian counteroffensive.

Prigozhin said he was taking the decision in retaliation against Russia’s military leadership, which he accused of deliberately starving his troops of ammunition because they are jealous of Wagner’s success.

Prigozhin and Russia’s defense ministry have been in a one-sided public feud for months. Prigozhin claims it's now reached a breaking point, delivering a blistering attack on Russia's senior military command in the video announcing the withdrawal. He accused them of being "cowards" and of denying Russians a victory in Bakhmut because of their "petty envy."

Ukrainian military officials said they did not believe Wagner forces would retreat from Bakhmut, suggesting they believed his announcement was an attempt to excuse his failure to seize the city by May 9 as he pledged. A spokesman for Ukraine's eastern command, Sergiy Cherevatyi, said Wagner was running out of fighters, not ammunition.

-ABC News' Patrick Reevell