US President Donald Trump has said he is "not happy" with deadly Russian strikes on Kyiv and that President Vladimir Putin should "stop" – but has not said if further action might be taken against Russia.
Overnight into Thursday, the attacks on the Ukrainian capital killed at least 12 people and injured 90 others.
The US president said he is "putting a lot of pressure" on both sides to end the war in Ukraine, following the deadliest attacks Kyiv has seen since last July.
It is the latest road bump in efforts to advance a peace deal between the two countries – something the US president said he would be able to quickly do as part of his election campaign last year.
In rare criticism of Russian President Vladimir Putin, Trump wrote in a post on Truth Social: "Not necessary, and very bad timing. Vladimir, STOP!"
The attack has come at a time of growing pressure on Ukraine and President Volodymyr Zelensky to accept Russian occupation of its territory as part of a peace deal.
On Thursday, Trump appeared alongside Norway's Prime Minister Jonas Gahr Støre at the White House and said he had "no allegiance to anybody" only an "allegiance to saving lives".
While he admitted frustration with Putin, Trump said he would wait a week "to see if we have a deal" – but that "things will happen" if the bombings do not end.
Trump's special envoy Steve Witkoff is expected to hold talks with Putin in Moscow later on Friday.
President Volodymyr Zelensky responded to the attacks during a visit to South Africa, saying he felt the US could be more forceful with Russia to secure a ceasefire.
- South Africa and Ukraine woo each other – as relationships with Trump turn sour
"We believe that if more pressure is applied to Russia, we'll be able to make our positions closer," Zelensky told reporters.
When asked if he would be willing to make any concessions, Zelensky said the fact that Ukraine is prepared to negotiate with Russia at all is a "huge compromise" and a "ceasefire must be the first step".
"If Russia says it is ready to cease fire, it must stop massive strikes against Ukraine. It is Ukrainians who are running out of patience, because it is us who are under attack, and no one else," he added.
The attack caused Zelensky to cut his trip short and return home.
In an interview with CBS's Face the Nation TV programme, Russian Foreign Minister Sergei Lavrov said that "we only target military goals or civilian sites used by the military".
Lavrov provided no evidence to back his claim.
He added that some elements needed to be "fine tuned" for Russia to agree to the US-proposed peace deal.
Before the attack on Kyiv, the week had seen a fraying of the already imperilled relationship between Trump and Zelensky – as the US president has suggested the need for Ukraine to make land concessions as part of a peace deal.
On Wednesday, Trump claimed a deal to end the war was "very close", but that Zelensky's refusal to accept US terms "will do nothing but prolong" the conflict.
Ukraine has long said it will not give up Crimea, a southern peninsula illegally annexed by Russia in 2014.
On Wednesday, US Vice-President JD Vance laid out the US vision for a deal, saying it would "freeze the territorial lines […] close to where they are today", and added that Ukraine and Russia "are both going to have to give up some of the territory they currently own".
- Trump criticises Zelensky as Ukraine refuses Russian control of Crimea
When asked by reporters at the White House this week about whether the administration was looking to recognise Russia's sovereignty over Crimea, Trump said he just wanted to see the war end.
Recognising Russia's illegal occupation of Crimea would not only be politically impossible for Zelensky to accept, it would also be contrary to post-war international legal norms that borders should not be changed by force.
"We've shown them the finish line," Secretary of State Marco Rubio said on Thursday in the Oval Office, where he appeared alongside Trump and the Norwegian prime minister.
"We need both of them to say yes, but what happened last night with those missile strikes should remind everybody of why this war needs to end."
President Zelensky's visit to South Africa, during which he met President Cyril Ramaphosa, signalled a dramatic improvement in the once-strained relations between the two nations.
Ramaphosa said during a news briefing alongside Zelensky that he was deeply concerned about the ongoing conflict in Ukraine. He also reiterated South Africa's commitment to speaking to all parties in the conflict.
He added that he had spoken to both Putin and Trump on the need to bring an end to the conflict.
Ramaphosa, in the briefing, did not go into whether Ukraine should cede territory to Russia.
The US was one of Ukraine's closest allies until the re-election of Trump in November. Now Ukraine is keen to broaden its pool of international partners – particularly in Africa where many countries have strong links with Russia.
South Africa has also suffered from strained relations with Washington, which has expelled its ambassador and removed aid funding.
South Africa says its non-aligned position puts it in a prime position to help bring about a peace deal with Russia.