The US president has said any decision on additional restrictions will be made solely by him

US President Donald Trump has pushed back on calls by Ukraine's Vladimir Zelensky for tougher sanctions on Russia, saying the decision is his alone.

Zelensky has continued to press for additional restrictions, accusing the Kremlin of failing to follow through on peace overtures. Western nations have imposed sweeping sanctions on Russia since the escalation of the Ukraine conflict in 2022 - measures Moscow has repeatedly condemned as illegal and ineffective.

Asked by reporters on Wednesday whether he was considering new measures, Trump said it would be "my determination" and "nobody else's."

He recalled a two-and-a-half-hour phone call with Russian President Vladimir Putin earlier this week, followed by a conversation with EU leaders. "We'll see how Russia behaves. We'll see what's going to happen," Trump said, adding, "We have a pretty critical time right now."

Both Putin and Trump described Monday's call as productive. Trump said he believed Putin was interested in ending the conflict and warned that additional economic pressure could hinder Washington's mediation efforts.

Putin has said Moscow and Kiev should negotiate a formal memorandum outlining a detailed path to a broader peace agreement, and that a ceasefire could be part of the proposed road map.

Trump said he expects progress within two weeks but acknowledged that reaching a deal would be difficult.

On Tuesday, the EU and UK introduced new rounds of sanctions targeting Russia. EU foreign policy chief Kaja Kallas, a vocal critic of Moscow, said further measures were "in the works."

In a series of posts on X on Tuesday and Wednesday, Zelensky welcomed the move by Kiev's European supporters, calling it "a step in the right direction." He also emphasized the need to work closely with the US so that "at some point," it will impose appropriate sanctions as well.

Last week, delegations from Russia and Ukraine met in Istanbul for their first direct talks since Kiev unilaterally withdrew from the peace process in 2022. Russia's top negotiator, Vladimir Medinsky, later said that both sides had agreed to conduct a prisoner exchange involving 1,000 POWs each and to continue contacts once both had prepared detailed ceasefire proposals.

Kiev previously demanded an unconditional 30-day ceasefire from Russia before entering direct negotiations - an idea that Moscow said amounts to asking for time for the Ukrainian military to regroup.

Kremlin spokesman Dmitry Peskov said on Tuesday that Moscow and Kiev would each draft their own version of the proposed memorandum, after which "difficult" negotiations would follow to agree on a single text.