DUBAI, United Arab Emirates — U.S. negotiators worked on a proposed partial ceasefire in the the 3-year-old war in Ukraine on Monday, meeting representatives from Russia one day after holding separate talks with a team from Kyiv.

It has been a struggle to reach even a limited, 30-day ceasefire — which Moscow and Kyiv agreed to in principle last week — with both sides continuing to attack each other with drones and missiles.

One major sticking point is what targets would be off-limits to strike, even after U.S. President Donald Trump spoke with the countries’ leaders, because the parties disagree.

While the White House said “energy and infrastructure” would be covered, the Kremlin declared that the agreement referred more narrowly to “energy infrastructure.” Ukrainian President Volodymyr Zelenskyy has said he would also like to see infrastructure like railways and ports protected.

Talks Monday in the Saudi capital of Riyadh are expected to address some of those differences, as well as a potential pause in attacks in the Black Sea to ensure the safety of commercial shipping.

U.S. and Russian representatives met in the morning, Russia’s state Tass and RIA-Novosti news agencies reported. The U.S. and Ukrainian teams met Sunday.

Serhii Leshchenko, an adviser to the Ukrainian presidency, said the delegation remained in Riyadh on Monday and expected to meet again with the Americans.

Grigory Karasin, head of the foreign affairs committee in the Russian parliament’s upper house and a participant in Monday’s talks, told the Interfax news agency the negotiations were going on in a “creative way” and that the U.S. and Russian delegations “understand each other’s views.”

Ukraine, Russia Continue to Launch Attacks

Meanwhile, both Russia and Ukraine continued to launch attacks across their borders.

The Russian Defense Ministry said Monday a Ukrainian drone attacked an oil pumping station in southern Russia that serves a pipeline carrying Kazakhstan’s Caspian Sea oil to the Russian port of Novorossiisk for export. It said the drone was downed before it could reach the pumping station.

Kremlin spokesman Dmitry Peskov said Monday the Russian military has been fulfilling President Vladimir Putin’s order to halt attacks on energy facilities for 30 days. He has accused Ukraine of derailing the partial ceasefire with attacks on Russia’s energy facilities, including a gas metering station in Sudzha in Russia’s Kursk region.

Ukraine’s military General Staff rejected Moscow’s accusations and blamed the Russian military for shelling the station, a claim Peskov called “absurd.”

Zelenskyy said Sunday evening that “since March 11, a proposal for an unconditional ceasefire has been on the table, and these attacks could have already stopped. But it is Russia that continues all this.”

He added that Ukraine’s partners — “the U.S., Europe, and others around the world” — should increase pressure on Russia “to stop this terror.”

Zelenskyy has emphasized that Ukraine is open to Trump’s proposal of a full, 30-day ceasefire. Putin has made a complete ceasefire conditional on a halt of arms supplies to Kyiv and a suspension of Ukraine’s military mobilization — demands rejected by Kyiv and its Western allies.

Speaking on “Fox News Sunday,” Trump’s special envoy Steve Witkoff said he expected “some real progress” at talks and that a pause in hostilities by both countries in the Black Sea would “naturally gravitate into a full-on shooting ceasefire.”

China Rules out Supplying Peacekeeping Forces

Asked about reports speculating that China might send peacekeepers to Ukraine to enforce any peace deal, Chinese Foreign Ministry spokesperson Guo Jiakun responded Monday with an unequivocal no.

“Let me stress that the report is completely false. China’s position on the Ukraine crisis is clear and consistent,” Guo said at a briefing.

China has provided Russia with trade earnings from oil and other natural resources, along with diplomatic backing, but has not given any weapons or sent any personnel. China is, however, on close terms with North Korea, which has sent troops to fight alongside the Russian army.

Ukrainian Railways Hit by Cyberattack

A “massive targeted cyberattack” hit Ukrainian state railway operator Ukrzaliznytsia on Sunday, the company wrote on Telegram, adding that it was working to restore its systems on Monday. The company said the attack did not affect train movements or schedules but disrupted its online booking system.

“The railway continues to operate despite physical attacks on the infrastructure, and even the most vile cyberattacks cannot stop it,” the company wrote.

Meanwhile, Ukraine’s Special Operations Forces claimed Monday it destroyed four military helicopters in Russia’s Belgorod region with the use of U.S.-supplied HIMARS rocket systems. It published drone footage on its Telegram page of what it said was the attack.

The strikes occurred at a concealed “jumping-off point” for Russian aircraft used in surprise attacks on Ukrainian forces, the group said.

A Russian missile struck the northern city of Sumy, across the border from Russia’s Kursk region, hitting residential buildings and a school, said regional head Volodymyr Artiukh. Children at the school were being evacuated at the time, and all were safe, he added.

But the regional prosecutor’s office said 65 people were injured, including 14 children.

Earlier, Russia fired 99 attack and decoy drones into Ukraine overnight, according to Ukraine’s air force, of which 57 were shot down.