The Trump administration has trumpeted a breakthrough in talks with Russia this month, claiming that Mr. Putin had accepted a proposal for the West to provide security guarantees for Ukraine as strong as Article 5 of the NATO charter, which stipulates that an attack on one alliance member is considered an attack on all.

Foreign Minister Sergei Lavrov said any Western security guarantees for Ukraine in an eventual peace deal could only be enacted with Moscow’s cooperation—essentially rendering them useless against another Russian invasion.

The US president says Russia's Vladimir Putin would face a "rough situation" if he doesn't co-operate in the peace process.

T wo German fighter jets were scrambled to the Romanian-Ukrainian border on Tuesday night in response to a Russian drone attack in the frontier region, Romania's Defense Ministry said in a statement.