Still, Zelenskyy characterized the meeting as positive, AP reported. “In my opinion, he does not want an escalation with the Russians until he meets with them,” the Ukrainian told reporters. “We share President Trump’s positive outlook if it leads to the end of the war. After many rounds of discussion over more than two hours with him and his team, his message, in my view, is positive — that we stand where we stand on the line of contact, provided all sides understand what is meant.” Some Ukrainians saw the denial as a blow. 

Russia’s Vladimir Putin had phoned Trump on Thursday. Among other things, the Washington Post reported, Putin demanded “that Kyiv surrender full control of Donetsk, a strategically vital region in eastern Ukraine, as a condition for ending the war, two senior officials familiar with the conversation.” That “suggests he is not backing away from past demands that have left the conflict in a stalemate, despite Trump’s optimism about securing a deal, the officials said, speaking on the condition of anonymity to describe sensitive closed-door discussions.”

Putin wants Trump to cede what his forces have been unable to capture. Russian-backed separatists since 2014 and Russia’s military since 2022 have sought to conquer the Donetsk Oblast, a heavily fortified region that includes vital portions of Ukraine’s defense industry. “Russian forces currently have no available means of rapidly enveloping or penetrating the fortress belt, which would likely take several years to seize at their current rate of advance,” the Institute for the Study of War posted on Sunday. “Ceding Donetsk Oblast to Russia would allow Russian forces to avoid a long and bloody struggle and continue fighting into deep rear areas of Ukraine from new positions…”

Putin initiated the phone call, a move the New York Times called “a telling acknowledgment of a Russian priority as important as any battlefield in Ukraine: appeasing Mr. Trump. Even as Mr. Putin has pounded Ukrainian cities and waged grinding warfare in the country’s east, he has invested dozens of hours into flattering Mr. Trump, dangling the prospect of Russian-American business deals and sending the message that Russia is open to talks to end its invasion. 

“The tactic has helped Mr. Putin head off repeated deadlines and sanction threats by the American president without curtailing Russia’s war effort.” Read more about Putin’s approach to Trump, here.

Ukrainian strike closes Russian gas plant. ABC News: “Ukrainian drones struck a major gas processing plant in southern Russia, sparking a fire and forcing it to suspend its intake of gas from Kazakhstan, Russian and Kazakh authorities said Sunday.” The Orenburg plant is one of the largest in the world. “Kyiv has ramped up attacks in recent months on Russian energy facilities it says both fund and directly fuel Moscow’s war effort,” ABC wrote, here.

Welcome to this Monday edition of The D Brief, a newsletter dedicated to developments affecting the future of U.S. national security, brought to you by Bradley Peniston and Lauren C. Williams. It’s more important than ever to stay informed, so thank you for reading. Share your tips and feedback here. And if you’re not already subscribed, you can do that here. On this day in 1922, Army test pilot Lt. Harold Harris became the first person to bail out of a plane and survive using a parachute.

Caribbean ops

7th deadly strike. On Sunday, Defense Secretary Pete Hegseth said Thursday’s strike on a boat in the Caribbean Sea had killed “three male narco-terrorists” on “a vessel affiliated with Ejército de Liberación Nacional (ELN), a Designated Terrorist Organization.” He said the boat was “known by our intelligence to be involved in illicit narcotics smuggling,” but provided no evidence.

Two people survived the strike, a first for the no-notice strikes on vessels in international waters, which have killed 27. The Trump administration is returning the survivors to their home countries of Colombia and Ecuador, the New York Times reported. 

The strikes have caused a rift between the United States and Colombia, which CNN says had “previously been Washington’s most reliable ally in South America on national security and defense.” President Gustavo Petro has complained about the strikes, which he—and many legal experts—have called illegal assaults on his country’s citizens. On Sunday, Trump responded by saying that he would end some form of U.S. aid to Colombia. “The US has provided about $210 million in assistance to Colombia this fiscal year, including about $31 million in agricultural support, according to data from the US Department of State. It was not immediately clear which payments Trump was referring to Sunday,” CNN wrote.

Gaza

Sunday violence shakes Gaza ceasefire. Militants in Gaza fired an anti-tank missile at Israeli forces, killing two troops, said Israeli officials, who said they responded with strikes on Hamas targets including field commanders, gunmen, a tunnel, and weapons depots. On Monday, CNN reported that the Israeli strikes had killed at least 44 people. Reuters: “At least one strike hit a former school sheltering displaced people in the area of Nuseirat, residents said.” More, here.

Both sides subsequently committed to uphold the week-old ceasefire, which each blaming the other for breaking. More from CNN, here.

The White House rushed mediators to the region, including envoy Steve Witcoff and Trump son-in-law Jared Kushner, and Vice-President JD Vance was to arrive on Tuesday. Reuters reported that they “were expected to push to shore up the truce and then start talks on the next, more difficult, phase of the 20-step plan during their visit.”

Around the Defense Department

Army to build $50 million border fence along Arizona military training range. The Army Corps of Engineers began building 15 miles of border fence along the Barry M. Goldwater Training Range in Yuma, Ariz., yesterday, the Army’s civilian installations boss, Defense One’s Meghann Myers reports. The fence will replace existing easily penetrable mesh fencing on the southern border with Mexico, where crossings have forced some shutdowns of pilot and ground crew training. “When incursions occur and illegal border crossers get into that area, the ranges must close,” Jordan Gillis, the assistant Army secretary for energy and installations, told reporters. “That delays the training exercises. It diverts our time and our resources and ultimately impacts readiness.” Read on, here. 

Upgraded comms? In more Army news, the service plans to test its next-generation command and control prototype for the second time since awarding the contract in July. The 4th Infantry Division will kick off Ivy Sting 2 at Fort Carson, Colo., where soldiers will test how the system handles deconflicting airspace before firing weapons and other scenarios, Myers reports. “How can we have the commanders doing their updates, doing their planning, but more importantly, how can we then enact that plan and shorten the time it takes to conduct fires?” Zach Kramer, head of Anduril’s mission command office, told Defense One. Here’s the full story.