U.S. President Donald Trump said on Thursday that a phone call earlier in the day with Vladimir Putin resulted in no progress at all on efforts to end the war in Ukraine, while a Kremlin aide said the Russian president reiterated that Moscow would keep pushing to solve the conflict’s “root causes.”

The two leaders did not discuss a recent pause in some U.S. weapons shipments to Kyiv during the nearly hour-long conversation, according to a readout provided by Putin aide Yuri Ushakov, Reuters reported.

U.S. attempts to end Russia’s war in Ukraine through diplomacy have largely stalled, and Trump has faced growing calls – including from some Republicans – to increase pressure on Putin to negotiate in earnest.

Within hours of the call’s conclusion, an apparent Russian drone attack sparked a fire in an apartment building in a northern suburb of Kyiv, Ukrainian officials said, indicating little change in the trajectory of the conflict.

In Kyiv itself, Reuters witnesses reported explosions and sustained heavy machine-gun fire as air defense units battled drones over the capital, while Russian shelling killed five people in the eastern part of the country.

“I didn’t make any progress with him at all,” Trump told reporters in brief comments at an air base outside Washington, before departing for a campaign-style event in Iowa.

Ukrainian President Volodymyr Zelenskiy, meanwhile, told reporters in Denmark earlier in the day that he hopes to speak to Trump as soon as Friday about the ongoing pause in some weapons shipments, which was first disclosed earlier this week.

Trump, speaking to reporters as he left Washington for Iowa, said “we haven’t” completely paused the weapons flow but blamed his predecessor, Joe Biden, for sending so many weapons that it risked weakening U.S. defenses.

“We’re giving weapons, but we’ve given so many weapons. But we are giving weapons. And we’re working with them and trying to help them, but we haven’t. You know, Biden emptied out our whole country giving them weapons, and we have to make sure that we have enough for ourselves,” he said.

The diplomatic back-and-forth comes as the U.S. has paused shipments of certain critical weapons to Ukraine due to low stockpiles, sources earlier told Reuters, just as Ukraine faces a Russian summer offensive and increasingly frequent attacks on civilian targets.

Putin, for his part, has continued to assert he will stop his invasion only if the conflict’s “root causes” have been addressed – Russian shorthand for the issue of NATO enlargement and Western support for Ukraine, including the rejection of any notion of Ukraine joining the NATO alliance.

Russian leaders are also angling to establish greater control over political decisions made in Kyiv and other Eastern European capitals, NATO leaders have said.

The pause in U.S. weapons shipments caught Ukraine off-guard and has generated widespread confusion about Trump’s current views on the conflict, given his statement just last week that he would try to free up a Patriot missile defense system for use by Kyiv.

Ukrainian leaders called in the acting U.S. envoy to Kyiv on Wednesday to underline the importance of military aid from Washington, and caution that the pause in U.S. weapons shipments would weaken Ukraine’s ability to defend against intensifying Russian air strikes and battlefield advances.

The Pentagon’s move has meant a cut in deliveries of the Patriot defense missiles that Ukraine relies on to destroy fast-moving ballistic missiles, Reuters reported on Wednesday.

Ushakov, the Kremlin aide, said that while Russia was open to continuing to speak with the U.S., any peace negotiations needed to occur between Moscow and Kyiv.

That comment comes amid some indications that Moscow is trying to avoid a trilateral format for any potential peace negotiations. The Russians asked American diplomats to leave the room during such a meeting in Istanbul in early June, Ukrainian officials have said.

Trump and Putin did not talk about a face-to-face meeting, Ushakov said.