Washington and Moscow went head-to-head in Munich on Saturday, accusing each other of undermining global security and Ukrainian sovereignty.

While US vice president Joe Biden warned Moscow that the US and Europe would stand united behind Kiev, Russian foreign minister Sergey Lavrov attacked US “obsession” with global dominance and the “connivance” of the EU in the region.

In a day of robust public exchanges and frantic closed-door diplomacy, Ukrainian president Petro Poroschenko made an impassioned plea to western leaders to boost Kiev’s defence capabilities, saying Ukraine “had a right to defend our people”.

His remarks openly contradicted German chancellor Angela Merkel who dismissed defensive weapons for Ukraine, an issue that will dominate her trip to Washington on Monday.

Mr Biden recalled his Munich address seven years ago to offer Russia a “reset” in bilateral relations that resulted in nuclear arms reductions and closer co-operation at the UN.

“We all invested in a type of Russia we hoped and still hope will emerge one day,” he said. “Unfortunately Mr Putin has chosen a different path.”

Now he said Moscow repressed critics at home, disrespected others’ territorial integrity and disregarded Russia’s own international commitments on both fronts.

Balanced message

Amid heated discussion on whether to arm Ukraine in its battle against pro-Russian separatists, Mr Biden delivered a carefully balanced message. He welcomed the Franco-German diplomatic effort in Moscow and echoed Chancellor Merkel’s doubt that a military solution was possible.

But with an eye on the heated debate in Washington, which spilled over to Munich, he added: “We believe the Ukrainian people have a right to defend themselves.”

After tri-lateral talks with Mr Biden and Dr Merkel, Mr Poroschenko said the current deterioration in eastern Ukraine was the result of “a lack of defence capability”.

“We are not going to use these weapons to kill people but to make our defence more efficient,” he said.

Sitting on a panel with Mr Poroschenko, Lithuanian president Dalia Grybauskaite urged western allies to use “all means necessary” to support Ukraine against Russia.

“If we betray Ukraine we betray ourselves, after Ukraine, we will be next,” said Dr Grybauskaite.

Robust attack

Earlier, Russian foreign minister Sergey Lavrov delivered a robust attack on the US and EU framing of the Ukraine crisis.

Mr Lavrov said US-EU “interference” in Ukrainian sovereign affairs was part of a wider, long-term pattern of undermining of international agreements and, with it, global security.

The EU “under US influence” had worked to escalate the Ukraine conflict by closing the door on a common security talks and refusing to include Moscow in EU-Kiev talks on an association agreement.

“Our western partners issued indulgences and pardoned Kiev forces who started revolutionary efforts,” he said, “dubbing terrorists all citizens who were not in agreement with the anti-constitutional coup d’etat.”

In an angry speech, as translators struggled to keep up, Mr Lavrov said Crimea’s accession to the Russian federation “complies with the UN Charter on self-determination” – prompting snorts from the Munich conference hall.

After a meeting with Mr Lavrov, Nato secretary general Jens Stoltenberg spoke for many delegates in Munich by saying “we assess the situation in Ukraine in very different ways”.