The White House said Tuesday that Ukraine and Russia had agreed to cease fighting in the Black Sea and halt strikes on energy facilities. It would be the first significant step toward the full cease-fire the Trump Administration had been pushing, but it still would fall short of that goal.

The agreements came after three days of intense negotiations in Riyadh, the capital of Saudi Arabia, during which delegations from Ukraine and Russia met separately with U.S. mediators. Rustem Umerov, Ukraine’s defense minister, confirmed the agreements in a message posted on social media. There was no immediate reaction from Russia.

The White House released two different statements saying it had separately struck deals with Ukraine and Russia on the maritime and energy attacks. The statements added that Washington, Kyiv and Moscow welcomed the involvement of third countries in “supporting the implementation of the energy and maritime agreements.”

It was not immediately clear how and when the energy and maritime agreement would be implemented. Mr. Umerov, who led his country’s delegation in Riyadh, said “additional technical consultations” would have to be held as soon as possible for “the implementation, monitoring and control of the arrangements.”

Both Russia and Ukraine rely on the Black Sea for commodity exports. In mid-2022, they brokered a deal allowing Ukraine to ship grain through the sea, but Russia withdrew from the agreement a year later, arguing that Western sanctions were severely limiting its ability to export agricultural products.

Russia then threatened all commercial vessels heading to and from Ukraine, aiming to strangle its seaborne exports. In response, Ukraine’s military started a campaign that pushed the Russian navy out of the western parts of the Black Sea, destroying many of its warships and striking its headquarters in Russian-occupied Crimea. The operation allowed Ukraine to establish a new shipping corridor in the Black Sea and return seaborne grain exports to near-prewar levels.

Mr. Umerov said that under the deal, “all movement by Russia of its military vessels outside of Eastern part of the Black Sea will constitute violation of the spirit of this agreement,” and that Ukraine would have “full right to exercise right to self-defense.”

The White House statements said both Russia and Ukraine had agreed to “eliminate the use of force in the Black Sea.” It was not immediately clear if this would result in a halt on strikes on port infrastructure, which the Ukrainians said was discussed during the talks. Kyiv has also been interested in restarting operations in frontline Ukrainian port cities like Mykolaiv and Kherson, where the nearby fighting has forced them to shut down.