Sgt. 1st Class Andrew Dickson/U.S. Army/AP
US Army Sgt. Ian Ketterling, gunner for Alpha Battery, 1st Battalion, 3rd Field Artillery Regiment, 17th Field Artillery Brigade, prepares the crane for loading the Army Tactical Missile System (ATACMS) on to the High Mobility Artillery Rocket System (HIMARS) in Queensland, Australia, on July 26, 2023.
Rio de Janeiro CNN  — 

A major decision by the United States to allow Ukraine to fire long-range missiles deeper inside Russian territory has complicated a potential western diplomatic thaw with Russia as dozens of world leaders gather this week.

Sunday’s decision was viewed by many western leaders as a way to position Ukraine for success ahead of a change in American leadership, with the incoming president skeptical of continued US assistance.

But it also complicated the diplomatic dance leaders attending the G20 summit must partake in as they navigate the complex geopolitical dynamics of the bloc.

Russia “will perceive launches of long-range missiles guided by US military experts as a qualitatively new phase of war by the West,” Russian Foreign Minister Sergey Lavrov said during a news conference at the summit, according to Russian state media TASS.

Lavrov attended the G20 in place of Russian President Vladimir Putin, who faced questions about whether he could be arrested for war crimes on international soil. Days after Ukrainian President Volodymyr Zelensky called on Brazilian authorities to arrest Putin, the Russian leader said he would skip the summit to avoid disrupting it.

Amid the change in strategy – which Biden had deliberated over for months – the president and his team steered clear of Lavrov on the ground in Rio.

When Biden missed a photo with other leaders on Monday, speculation abounded that he was trying to avoid being photographed with Lavrov. The White House denied that, citing a logistical snafu.

Still, neither Biden nor his delegation held talks with Lavrov or his team, US officials said. And Biden and Lavrov’s fluid schedules meant that they were not photographed together with other world leaders.

But some Western allies, sensing a sea change in the US approach to the conflict once Donald Trump takes office, appear to be weighing a shift in their own stance toward Moscow.

German Chancellor Olaf Scholz spoke to Putin by phone the week before the summit. In his remarks at the close of the summit, Lavrov also hailed the German government’s refusal to send Taurus cruise missiles to Ukraine as a “responsible stance,” TASS reported.

And onsite in Rio, French President Emmanuel Macron could be seen shaking the hand of Lavrov, standing in the row behind him during a “family photo” of attendees.

In Rio, the pending Trump presidency shadowed nearly every discussion of the Ukraine conflict. Leaders here are acutely aware of Trump’s views toward the war, but are less certain of how that will manifest in policy once he takes office.

It’s not clear, for example, whether Trump would uphold Biden’s decision on allowing Ukraine the long-range capability, a step that NATO leaders had been encouraging for months. Trump’s incoming national security adviser, Florida Rep. Mike Waltz, questioned the decision in an interview Monday.

“It’s another step up the escalation ladder and nobody knows where this is going,” he said on Fox News, adding he hadn’t been given a heads up by the outgoing administration about the change in policy.

Officials in Rio declined to say whether Biden had raised the issue of the missiles with Trump during their two-hour meeting in the Oval Office last week.

“The two presidents discussed a wide range of issues. We’ve been pretty careful not to read that conversation out in any detail. Certainly, the conversation included all of the major issues of geopolitical significance, but I’m not going to get into the details of it,” deputy national security adviser Jon Finer said.

There had been hope among western officials of a strong statement denouncing Russia’s invasion at the conclusion of the summit. In particular, European diplomats made a late-stage push to strengthen the language following Russia’s massive drone and missile attack on Sunday, according to people familiar with the talks.

Ultimately, the effort was dropped when it appeared other countries were not on board. The language in the final leaders statement was watered down from previous years, including broad references to “human suffering” and “negative added impacts of the war” without explicit condemnation of Russia.

The Ukraine war generated only one paragraph in the final document, compared to several that were included in the final document produced by the G20 last year in New Delhi — which itself was watered down from the previous year.

As the summit was concluding, it was evident that tensions between the US and Russia were only ratcheting up. Russia announced as the second day of the summit was getting underway that it would update its nuclear doctrine to consider aggression from any non-nuclear state – but with the participation of a nuclear country – a joint attack on Moscow.

American officials were unsurprised to learn Moscow had updated its nuclear doctrine following Biden’s decision on long-range missiles.

“Russia had been signaling its intent to update its doctrine for several weeks,” a US official said in response to the doctrine update, adding that so far the US has not observed any updates to Russia’s nuclear posture — and thus see no reason to change the US stance.

“This is more of the same irresponsible rhetoric from Russia, which we have seen for the past two years,” the official said.

In his closing remarks, Lavrov sought to downplay the change in the fine print on its nuclear posture – shifting blame instead to the West.

“The update of the military doctrine does not add anything which would be different… from the American doctrine or documents on what to do with nuclear weapons,” according to Russian state media.