U.S. special envoy Steve Witkoff and Jared Kushner, President Donald Trump's son-in-law, have remained in touch with Ukrainian and Russian officials almost daily despite focusing on negotiating a permanent peace deal with Iran, The New York Times reported.

The war between Ukraine and Russia has escalated in recent weeks, shifting from a grinding front-line stalemate to a destructive exchange of long-range strikes on each other's critical infrastructure.

The Times reported that analysts describe the situation as one of the most volatile and dangerous periods since Russia's invasion of February 2022.

Witkoff and Kushner traveled to Doha, Qatar, this week for another round of indirect talks with Iran, even as Ukraine was launching more drones toward Moscow.

Meanwhile, Russia was readying its latest salvo targeting Kyiv, where at least 21 people were reported killed Thursday in overnight attacks.

A senior U.S. official, speaking to the Times on condition of anonymity because of the sensitivity of the talks, said Witkoff and Kushner have held in-person meetings with Ukrainian and Russian officials that have not been reported.

The official said Witkoff and Kushner were prepared to travel to Russia and Ukraine if there was something new to discuss, but they would not travel "for a photo op."

The last time Russian and Ukrainian officials are known to have met face-to-face with Witkoff and Kushner was in Switzerland in February, according to the Times.

In the months since, the Iran conflict has consumed their attention, even as the fighting escalated between Russia and Ukraine.

"We were focused on Iran," Trump said last month, suggesting the administration could renew its efforts to end the Ukraine war once Iran was "in the rearview mirror."

Trump has adopted a slimmed-down approach to high-stakes diplomacy in his second term.

The post of U.S. ambassador to Moscow has been vacant for more than a year, and acting U.S. Ambassador to Ukraine Julie Davis announced her resignation in April, effective June 27. 

Secretary of State Marco Rubio and other top diplomats have played a limited role on Ukraine, leaving Witkoff and Kushner as the pivotal players.

To Moscow and Kyiv, Witkoff and Kushner are valuable contacts with direct lines to Trump. They also represent a bottleneck without the diplomatic teams that would typically lay the groundwork for high-level talks.

Ukrainian President Volodymyr Zelenskyy voiced frustration to CBS News on Thursday, saying he was still waiting for them to visit Ukraine, according to the Times.

"I understand that there are challenges in the Middle East," he said, adding, "but we need more, more than words."

Witkoff and Kushner, who helped broker a ceasefire last year in Israel's war against Iranian-backed Hamas terrorists in the Gaza Strip, are real estate developers who describe themselves as dealmakers who eschew the staid traditions of diplomacy, according to the Times.

The senior U.S. official told the newspaper that approach means they juggle multiple negotiations at a time, just as they did in their business careers and as Kushner did during Trump's first term, when he served as a White House adviser. Kushner played a major role in brokering the Abraham Accords.

In Moscow, officials are also eager for Witkoff and Kushner to reengage, the Times reported, citing two people close to the Kremlin and two former diplomats who visited Moscow last week.

"The Russians are desperately waiting for the return of Witkoff and Kushner," said one of the former diplomats, Thomas Greminger, the head of a Swiss think tank who traveled to Moscow for a foreign policy conference.

"There's a lot of frustration about the two. At the same time, nobody has an alternative to U.S. facilitation."

Russian President Vladimir Putin values his relationship with Witkoff in particular, the two people close to the Kremlin said.

Putin sees Trump's close friend as a crucial channel for accomplishing Kremlin goals that only the U.S. can deliver, including an arrangement keeping Ukraine out of NATO.

But the Times reported that Russian officials have grown frustrated by the uneven nature of those visits and the lack of follow-up.

According to people familiar with the negotiations, they have voiced a desire for a more structured diplomatic process.