BRUSSELS, Belgium, May 20, 2025 (BSS/AFP) - EU foreign policy chief Kaja Kallas on Tuesday called for the United States to take "strong action" against Russia if Moscow does not agree to a ceasefire in Ukraine.

"America said that if Russia doesn't agree on an unconditional ceasefire, then there are going to be consequences. So we want to see those consequences, also from the US side," Kallas said at a meeting of EU ministers in Brussels.

Donald Trump said Russia and Ukraine would "immediately" start peace talks after he spoke with Vladimir Putin on Monday, despite the Russian leader rebuffing the US president's call for an unconditional truce.

Germany's defence minister Boris Pistorius said the call between the two leaders showed Putin was not "genuinely interested in peace". 

"He is still not ready for concessions, only talks about a ceasefire under his conditions," Pistorius said. 

German Chancellor Friedrich Merz said following a separate call between Trump and European leaders Monday that the EU would "increase pressure" on Moscow through more sanctions. 

The EU is to formally adopt a 17th round of sanctions on Moscow on Tuesday over its invasion of Ukraine targeting mainly the "shadow fleet" Russia uses to circumvent restrictions on oil exports.

A further package of sanctions has already been put on the table, but there are fears the EU has limited avenues to impose major pain on the Kremlin.

"We continue on working on the next strong package of sanctions to put more pressure on Russia so that they would also want peace," Kallas said.

"There are sanctions regarding the oil price cap, energy, also banking sector -- the sanctions that will hurt Russia's economy."