Russian President Vladimir Putin and Ukrainian President Petro Poroshenko have sparred in the media, but the two formally met for the first time on Tuesday at a meeting with the leaders of Kazakhstan, Belarus and the European Union in Minsk, Belarus. The meeting was about as frosty as everyone figured it would be.

Putin threatened to cut Ukraine out of the Commonwealth of Independent States (CIS), an open trade union between Russia, Kazakhstan and Belarus. He called Ukraine “an inseparable part of the [CIS],” and warned trade sanctions could be levied if Ukraine allowed EU products to cross tariff-free into the CIS. Putin said the conflict in Ukraine “cannot be resolved through further escalation of force without due consideration of the vital interests of the country’s southeast regions and without a peaceful dialogue with these regions’ representatives.”

Poroshenko demanded Russia stop sending weapons across the border. As the heads of state landed in Minsk, Russian soldiers were captured across the Ukrainian border. Russia’s defense ministry said it was a mistake, while Ukraine’s National Security and Defense Council said the group of soldiers were on a “special task” mission.