Russia and Ukraine have agreed to a naval ceasefire in the Black Sea in separate deals with the US, after three days of peace talks in Saudi Arabia, the BBC reported.
Washington said all parties would continue working toward a "durable and lasting peace" in statements announcing the agreements, which would reopen an important trade route.
They have also committed to "develop measures" to implement a previously agreed ban on attacking each other's energy infrastructure, the White House said.
But Russia said the naval ceasefire would only come into force after a number of sanctions against its food and fertiliser trade were lifted, the BBC reported.
US officials have been separately meeting negotiators from Moscow and Kyiv in Riyadh with the aim of brokering a truce between the two sides. The Russian and Ukrainian delegations have not met directly, the London-based news outlet reported.
Ukrainian President Volodymyr Zelensky said the deal to halt strikes in the Black Sea was a step in the right direction.
Russia abandons Black Sea outpost of Snake Island in victory fo...
"It is too early to say that it will work, but these were the right meetings, the right decisions, the right steps," he told a press conference in Kyiv.
"No-one can accuse Ukraine of not moving towards sustainable peace after this," he added, after US President Donald Trump had previously accused him of blocking a peace deal.
But shortly after Washington's announcement, the Kremlin said the Black Sea ceasefire would not take effect until sanctions were lifted from Russian banks, producers and exporters involved in the international food and fertiliser trades.
The measures demanded by Russia include reconnecting the banks concerned to the SwiftPay payment system, lifting restrictions on servicing ships under the Russian flag involved in the food trade, and on the supply of agricultural machinery and other goods needed for the production of food.
It was unclear from the White House's statement when the agreement is meant to come into force.
When asked about lifting the sanctions, Trump told reporters: "We're thinking about all of them right now. We're looking at them."
Washington's statement on the US-Russia talks does say the US will "help restore Russia's access to the world market for agricultural and fertiliser exports".
Speaking in Kyiv, Zelensky described this as a "weakening of positions".
He also said Ukraine would push for further sanctions on Russia and more military support from the US if Moscow reneged on its commitments, according to the BBC.
Later, in his nightly address to Ukrainians, Zelensky accused the Kremlin of lying when it said the Black Sea ceasefire depended on sanctions being lifted.
Ukraine's Defence Minister Rustem Umerov said "third countries" could oversee parts of the deal, the BBC reported.
But he warned that the movement of Russian warships beyond the "eastern part of the Black Sea" would be treated as a violation of the agreement and a "threat to the national security of Ukraine".
"In this case Ukraine will have full right to exercise right to self-defence," he added.