Talks with US and Ukraine in Abu Dhabi were constructive but major challenges remain, Kremlin says

Negotiations aimed at ending Russia's invasion of Ukraine are yielding apparent signs of progress, but major challenges remain on the path to a final settlement, a senior Kremlin official said Monday.

Talks between envoys from Ukraine, Russia and the United States in recent days in Abu Dhabi were constructive and another round is planned for next week, Kremlin spokesman Dmitry Peskov told journalists.

He reported no major breakthrough so far, however, and added: "The very fact that these contacts have begun in a constructive way can be assessed positively, but there is still serious work ahead."

Officials revealed few details of the talks held on Friday and Saturday, which were part of a yearlong effort by the Trump administration to steer the sides toward a peace deal and end almost four years of all-out war.

While Ukrainian and Russian officials have agreed in principle with Washington's calls for a compromise, Moscow and Kyiv differ deeply over what an agreement should look like.

Meanwhile, the grinding war of attrition along the roughly 1,000-kilometer (600-mile) front line snaking through eastern and southern Ukraine has dragged on, and Ukrainian civilians are enduring another winter of hardship after Russian bombardment of cities in the rear.

U.S. President Donald Trump has set out deadlines for an agreement and threatened additional sanctions on Moscow, but Russian President Vladimir Putin apparently hasn't budged from his public demands.

Ukrainian President Volodymyr Zelenskyy also described the Abu Dhabi talks as constructive, although he noted that "addressed complex political issues ... remain unresolved."

A new round of trilateral meetings is expected later this week, Zelenskyy said, without giving a date.

Negotiators will return to the United Arab Emirates on Sunday for more talks, according to a U.S. official, speaking on condition of anonymity because they were not authorized to speak to the media. The weekend talks covered a broad range of military and economic matters and included the possibility of a ceasefire before a comprehensive deal, the official said.

Zelenskyy said Sunday that a document setting out U.S. security guarantees for Ukraine in a postwar scenario is "100% ready," although it still needs to be formally signed.

Kyiv has insisted on postwar American security commitments as part of any broader peace agreement with Moscow after Russia's 2014 illegal annexation of Crimea and support for separatist rebels in eastern Ukraine, followed by its full-scale invasion in February 2022.

Zelenskyy has acknowledged that there are fundamental differences between Ukrainian and Russian positions, though he said last week that peace proposals are "nearly ready."

A central issue is whether Russia should keep or withdraw from areas of Ukraine its forces have occupied, especially Ukraine's eastern industrial heartland called the Donbas, and whether it should get land there that it hasn't yet captured.

German Foreign Minister Johann Wadephul on Monday chided Moscow for its "stubborn insistence on the decisive territorial issue."

He said during a visit to Latvia that "if there is no agility here, I am afraid that the negotiations may take a long time or will not be successful now."

Russia's Defense Ministry said Monday that air defenses downed 40 Ukrainian drones late Sunday and early Monday, including 34 over the Krasnodar region and four over the Sea of Azov.

Krasnodar officials said drone fragments fell on two industrial plants in the city of Slavyansk, sparking fires that were extinguished. One person was injured, they said.

Ukraine's general staff said an oil refinery in the Krasnodar region was targeted by Ukrainian forces. The facility supplied the Russian military, it added.

Russian forces launched 138 drones at Ukraine overnight, 110 of which were shot down or suppressed, Ukraine's air force said, and 21 of them hit targets in 11 locations.