The Group of Seven most industralised nations on Thursday said it would do everything in its power to hold Russian President Vladimir Putin and his supporters personally responsible for the Ukraine invasion.

“We will spare no efforts to hold President Putin and the architects and supporters of this aggression, including the Lukashenko regime in Belarus, accountable for their actions,” the nations said in a statement after gathering Thursday.

G-7 leaders, including President Biden, said in a 19-point document that they would “step up” support for Ukraine and neighboring countries; ensure full implementation of sanctions against Russia; and take steps to reduce reliance on Russian energy.

The nations also called on Russia to suspend military campaigns in Ukraine, comply with international obligations at nuclear sites and stop threatening to use nuclear weapons. As the Russian military has stalled in its efforts to take control of Ukraine, U.S. and international officials have raised concerns that Moscow may escalate its aggression by using chemical warfare.

“I think it’s a real threat,” Biden said Wednesday before leaving the White House for Europe.

G-7 leaders said they were “appalled” by attacks against Ukrainian civilian infrastructure, including hospitals and schools, and would welcome international criminal investigations.

“We will work together to support the gathering of evidence of war crimes,” the statement said. “The siege of Mariupol and other Ukrainian cities, and the denial of humanitarian access by Russian military forces are unacceptable.”