Western leaders are on high alert following the 2 fatal explosion in Poland.

Following allegations on Tuesday that a missile strike 

 near Poland's border with Ukraine had killed two people

world leaders on three continents rushed to find explanations. 

This incident may have been one of the most

escalatory ones in the nearly nine-month conflict.

who is attending the G-20 summit in Indonesia

and national security adviser Jake Sullivan spoke

urgently with their Polish colleagues on the phone.