The United States reached deals on Tuesday with Ukraine and Russia to pause their attacks at sea and against energy targets, with Washington agreeing to push to lift some sanctions against Moscow.

The separate agreements are the first formal commitments by the two warring sides since the inauguration of President Donald Trump, who is pushing for an end to the warin Ukraine and a rapid rapprochement with Moscow that has alarmed Kyiv and European countries.

The U.S. agreement with Russia goes further than the agreement with Ukraine, with Washington committing to help seek the lifting of international sanctions on Russian agriculture and fertiliser exports, long a Russian demand.

The Kremlin said the Black Sea agreements would not come into effect unless links between some Russian banks and the international financial system were restored.

Ukrainian President Volodymyr Zelenskiy said this was untrue, and that the deals did not require sanctions relief to come into force.

"Unfortunately, even now, even today, on the very day of negotiations, we see how the Russians have already begun to manipulate," Zelenskiy said in his nightly video address. "They are already trying to distort agreements and, in fact, deceive both our intermediaries and the entire world."

Kyiv and Moscow both said they would rely on Washington to enforce the deals, while expressing scepticism that the other side would abide by them.

"We will need clear guarantees," said Russian Foreign Minister Sergei Lavrov. "And given the sad experience of agreements with just Kyiv, the guarantees can only be the result of an order from Washington to Zelenskiy and his team to do one thing and not the other."

Zelenskiy said the truce agreements would take effect immediately, and that if Russia violated them he would ask Trump to impose additional sanctions on Moscow and provide more weapons for Ukraine.

"We have no faith in the Russians, but we will be constructive," he said.

The deals were reached after parallel talks in Saudi Arabia that followed separate phone calls last week between Trump and the two presidents, Zelenskiy and Vladimir Putin.

Putin rejected Trump's proposal for a full ceasefire lasting 30 days, which Ukraine had previously endorsed.

"We are making a lot of progress," Trump told reporters on Tuesday, while adding there was "tremendous animosity" in the talks.

"There's a lot of hatred, as you can probably tell, and it allows for people to get together, mediated, arbitrated, and see if we can get it stopped. And I think it will work."