Kyiv. The Ukrainian air force shot down a Russian early warning and control plane that can spot targets up to 650 kilometers (400 miles) away and a key command center aircraft that relays information to troops on the ground in a significant blow to the Kremlin’s forces, Ukraine’s military chief said Monday.

The planes are fundamental tools in helping orchestrate Russian battlefield movements in Ukraine. Shooting them down, if confirmed, would be a landmark feat for Ukraine in the almost two-year war, as fighting along the front line is largely bogged down in trench and artillery warfare.

Russia has largely ensured its air dominance during the war, as Ukraine fights with its fleet of Soviet-era warplanes against Moscow's more modern aircraft.

Gen. Valeriy Zaluzhnyi, the commander-in-chief of the Ukrainian armed forces, didn't say how the two aircraft -- a Beriev A-50 and an Il-22 -- were brought down, but Ukraine has received sophisticated air defense systems from its Western allies.

Zaluzhnyi also did not say where the interceptions occurred, though he attached a video to his social media post with an airplane tracker showing two targets disappearing above the Azov Sea, which lies between Ukraine and Russia, north of the Crimea Peninsula and the Black Sea.

There was no immediate official comment from Moscow. Russian war bloggers said both planes had come under friendly fire, though they presented no evidence of that. They claimed the Il-22 was damaged but made a successful landing.

The A-50, which is topped with a large radar, typically carries a crew of 15. The Russian Air Force reportedly has been operating a fleet of nine such aircraft.

A February 2023 drone attack at an airfield in Belarus damaged a parked A-50, but Russian and Belarusian officials described the damage as minor.

The Il-22 is an airborne command post. It oversees military operations and sends radio signals to troops on the front line. The Russian Air Force reportedly has a dozen such planes.

Ukraine is eager to impress its Western supporters with its ability to deploy the advanced weapons it has received.

Ukrainian officials are striving to keep world attention on the war amid concerns that the conflict is slipping down the list of global priorities.

The United Nations appealed Monday for $4.2 billion to help people in Ukraine and displaced outside the country this year.

Martin Griffiths, the UN’s humanitarian chief, acknowledged that “the competition for funding is getting greater” because of crises elsewhere, including the Israel-Hamas war in Gaza.

Russia, meanwhile, was looking to deepen its ties with North Korea, whose foreign minister began a three-day visit to Moscow on Monday.

The Kremlin is eager to replenish its weapons stockpiles. It has in recent times turned to Iran and North Korea for supplies.

Pyongyang has likely supplied several types of missiles to Russia to support its war in Ukraine, along with its widely reported shipments of ammunition and shells, the US and its allies have alleged.

Russian and Iranian defense and foreign ministers spoke by phone Monday to discuss bilateral military and military-technical cooperation and regional security issues, according to official statements. They noted that the two countries are preparing to sign a landmark cooperation treaty.

Ukraine is also determined to build up its stocks for a protracted conflict and is “dramatically expanding” its domestic manufacturing capacity for military items, a U.S. think tank said.

Ukraine is well-positioned to succeed in its plans to make up for any shortfall in Western-supplied weaponry, the Institute for the Study of War said.

“Ukraine is heavily industrialized, with a highly educated and technically sophisticated population,” the think tank said late Sunday. “It had a massive arms industry during the Soviet period and continued to be a significant arms exporter after independence.”