A crater is seen near the small village of Przewodów, Poland, where Polish officials confirmed that two people were killed after an explosion.
Washington CNN  — 

President Joe Biden was asleep on the other side of the world when aides woke him up in the middle of the night there with urgent news: a missile had struck Poland and killed two people.

By 5:30 am local time in Bali, where the president was attending the G20 summit, Biden, still in a t-shirt and khakis, was on the phone with his Polish counterpart Andrzej Duda seeking clarity on where the missile had actually come from – a critical fact due to the potentially dire implications of a Russian missile strike on a NATO ally.

Secretary of State Antony Blinken, who was traveling with Biden, had also been roused with a knock on the door by his body man around 4 a.m. local time with news of the explosion, a US official said – news that most US officials only discovered from public reports and conversations with Polish officials.

Blinken and national security adviser Jake Sullivan spoke to their Polish counterparts and joined Biden for the call with Duda.

Polish officials first began hearing about a potential explosion in the eastern border village of Przewodów around 10 a.m. ET on Tuesday, or 11 pm Bali time, sources said, and information began trickling out publicly and briefed to allies around 1 p.m. ET, or 2 a.m. in Bali.

As the morning wore on there and more intelligence came in, it became clear to American officials examining satellite-based intelligence systems and speaking to their Polish counterparts that the missile, which landed on a Polish farm in the country’s far east, appeared to have been launched by Ukraine as part of its air defense systems.

After several anxious hours, Biden was the first to relieve some of the tension, telling reporters that initial information suggested the missile was not launched by Russia.

TOPSHOT - US President Joe Biden speaks about the situation in Poland following a meeting with G7 and European leaders on the sidelines of the G20 Summit in Nusa Dua on the Indonesian resort island of Bali on November 16, 2022.

The relief among US officials was palpable. Contrary to their worst fears the preliminary intelligence suggested that Russia had not deliberately attacked Poland, one official said. But for Biden and his advisers, the episode still represented a situation they had long feared: an unintentional strike in NATO territory, for which the implications and consequences remained murky.

Urging Ukraine to tread carefully

With the situation so fluid, Biden’s advisers urged calm and patience, including to Ukrainian officials.

Around an hour after the news broke of the incident, Volodymyr Zelensky said in his nightly address that “Russian missiles hit Poland,” calling it “a very significant escalation” that required a response.

Sullivan quickly called Zelensky’s office after those remarks, and urged officials to tread more carefully with how they were speaking about the incident, sources familiar with the call said. Biden and Zelensky did not speak on Tuesday night, despite requests by the Ukrainian leader to arrange a call, a source familiar with the matter said.

The US and Poland quickly agreed to work closely together on an investigation of the strike, and CIA Director Bill Burns met with Duda in Warsaw on Wednesday evening, a US official said. Just hours before, Burns had been hunkered down at the US embassy in Kyiv as Russian missiles struck the city.

But the incident has also created some cracks in the West’s alliance with Ukraine.

Biden and Duda have now both said publicly that the missile appeared to have originated with Ukraine’s air defense system—a claim Zelensky has continued to adamantly deny, which has frustrated Polish officials, sources said.

Polish President Andrzej Duda speaks during a press conference in Warsaw, Poland, 16 November 2022.

And although Biden spoke with Duda and NATO Secretary General Jens Stoltenberg in the aftermath of the strike, and held emergency talks with world leaders at the G20, the president had still not spoken directly with Zelensky by Wednesday afternoon, sources familiar with the matter told CNN.

Instead, Sullivan spoke to Zelensky’s chief of staff in the hours after the explosion, the sources said, and Blinken spoke with his Ukrainian counterpart Dmytro Kuleba.

Ukraine has also requested to join the investigatory team, m