American officials are reportedly saying initial findings suggest a missile that hit Poland was launched by Ukrainian forces.
The Associated Press news agency’s been told it was meant for incoming Russian fire.
Two people were killed in the east of the country yesterday.
The US President earlier revealed he thought it was "unlikely" Moscow was responsible.
Joe Biden is at the G20 summit in Indonesia as is Sky's Cordelia Lynch, who says talks on the incident have taken place.
"What we're seeing here is world leaders coalescing, trying to make clear what their statement is on this but not trying to jump the gun so there's caution being expressed from Biden and from others."
