LONDON — The prospects for a ceasefire between Russia and Ukraine are “in Moscow’s hands,” a top aide to Ukrainian President Volodymyr Zelenskyy said following successful U.S.-Ukraine talks in Saudi Arabia on Tuesday.

Andriy Yermak — the head of Zelenskyy’s office — was part of the Ukrainian delegation that met with American representatives in Jeddah, where both teams agreed to pursue a 30-day ceasefire and use the pause in fighting as a launchpad for full peace negotiations to end Russia’s 3-year-old invasion of its neighbor.

“Ukraine is ready to accept a 30-day ceasefire if Russia agrees,” Yermak wrote on Telegram on Wednesday morning. “This is a necessary step to begin work on real security guarantees and preparing the final terms of a peace agreement.”

“But now the key is in Moscow’s hands — the whole world will see who really wants to end the war and who is simply playing for time,” he added.

President Donald Trump’s return to office has put Ukraine in a strategic bind, no longer able to rely on the “ironclad” — if at times hesitant, according to many Ukrainians — American support during former President Joe Biden’s time in office.

Trump has aligned with Russian narratives about the conflict, framing Ukraine as the key impediment to peace, falsely blaming Kyiv for starting the war, undermining Zelenskyy’s legitimacy as president and seeking to recoup years of American aid via a controversial minerals sharing deal.

Last week, the Trump administration announced a freeze on U.S. military aid to and intelligence sharing with Ukraine. Tuesday’s meeting in Saudi Arabia saw that pause lifted, officials said.

Moscow has welcomed the radical U.S. shift in rhetoric and policy, which culminated in an explosive Trump-Zelenskyy Oval Office meeting last month.

Kyiv has been striving to prove its readiness for peace, while stressing that no deal can succeed without American security guarantees to deter repeat Russian aggression. Ukrainian leaders have also cast doubt on Russia’s apparent readiness to end the fighting and urged their U.S. partners to be wary of the Kremlin.

Following Tuesday’s talks, Zelenskyy wrote on Telegram of the 30-day ceasefire plan, “Ukraine accepts this proposal, we consider it positive, we are ready to take this step. The United States of America needs to convince Russia to do so.”

“We agree, and if the Russians agree, the silence will take effect at that very moment,” he added. “An important element in today’s discussions is America’s readiness to restore defense assistance to Ukraine and intelligence support.”

“Ukraine is ready for peace,” Zelenskyy wrote. “Russia must also show whether it is ready to end the war — or continue it. The time has come for the whole truth. I thank everyone who helps Ukraine.”

Trump told reporters Wednesday that he expects imminent further talks with Russian representatives. “Ukraine has agreed to it, and hopefully Russia will agree to it,” the president said of the proposed ceasefire.

“We’re going to meet with them later on today and tomorrow, and hopefully we’ll be able to wipe out a deal,” he continued. “But I think the ceasefire is very important. If we can get Russia to do it, that’ll be great. If we can’t, we just keep going on and people are going to get killed. Lots of people.”

When asked how close a ceasefire was, Trump responded, “Well, I hope it’ll be over the next few days. I’d like to see. I know we have a big meeting with Russia tomorrow, and some great conversations hopefully will ensue,” Trump said.

U.K. Prime Minister Keir Starmer in a statement said that “the ball is now in the Russian court.”

“This is an important moment for peace in Ukraine and we now all need to redouble our efforts to get to a lasting and secure peace as soon as possible,” he said in a statement on Wednesday.

Middle East envoy Steve Witkoff — who took part in the recent U.S. talks with both Ukraine and Russia — is due to visit Moscow “in the coming days,” according to a source familiar with the plans. Russia’s state-run RIA Novosti news agency also reported Wednesday that CIA Director Jim Ratcliffe spoke by phone with Sergey Naryshkin — the head of Russia’s Foreign Intelligence Service.

Russian Foreign Minister Sergei Lavrov, meanwhile, said in an interview published Wednesday that he does not believe Trump wants to provide security guarantees to Ukraine.

“He has his own view of the situation, which he regularly and directly states,” Lavrov said. “This war should never have started.”

Despite apparent progress in Jeddah, the fighting continues. Fierce combat is ongoing all along the front line, particularly in the western Russian Kursk region, where Moscow’s forces are pushing Ukrainian troops back from positions seized in a surprise August offensive.

Overnight, both sides launched drones across the shared border. Russia’s Defense Ministry reported the downing of 21 Ukrainian UAVs.

Ukraine’s air force reported three missiles and 133 drones launched into the country overnight. The air force said 98 of the drones were shot down and 20 lost in flight without causing damage. Odesa, Kharkiv, Sumy and Kyiv regions were affected, the air force said.

ABC News’ Kelsey Walsh contributed to this report.