NATO and G7 countries said on Wednesday they would remain in close contact to decide any possible reaction to a blast caused by a rocket that fell in Poland close to the Ukraine border and killed two people.
The joint statement followed an emergency meeting they held on the sidelines of a G20 summit in Indonesia, to discuss the explosions in NATO-member Poland, which were possibly caused by a Russian-made rocket.
"We agree to remain in close touch to determine appropriate next steps as the investigation proceeds," the leaders of the United States, Canada, the European Union, France, Germany, Italy, Japan, the Netherlands, Spain and the United Kingdom said in the common statement.
"We offer our full support for and assistance with Poland's ongoing investigation," the statement added.
Russia's defence ministry has denied that Russian missiles hit Polish territory, describing such reports as "a deliberate provocation aimed at escalating the situation".
The leaders also condemned Russian "barbaric" attacks against Ukrainian cities and civilian infrastructure.
Syrian rebels declared President Bashar al-Assad ousted after seizing control of Damascus on Sunday, forcing him to flee and ending his family's decades of rule after more than 13 years of civil war in a seismic moment for the Middle East.
Palestinian health officials said on Sunday that Israeli forces had shelled the Kamal Adwan Hospital in the northern Gaza town of Beit Lahiya, damaging electricity and oxygen pumps and disrupting urgent surgeries.
US President-elect Donald Trump said on Sunday that Russia's abandonment of Syrian President Bashar al-Assad led to his downfall, adding Moscow never should have protected him in the first place and then lost interest because of a war in Ukraine that never should have started.
The Kremlin said on Sunday that Russia was open to talks on Ukraine after US President-elect Donald Trump called for "an immediate ceasefire and negotiations".