WASHINGTON – US President Donald Trump appears to be losing patience with his Russian counterpart, Vladimir Putin, voicing disappointment on Monday just hours after threatening "severe tariffs" against Russia.

"I'm disappointed in him, but I'm not done with him. But I'm disappointed in him," Trump told BBC in an interview.

A few hours earlier, during a meeting with North Atlantic Treaty Organization (NATO) Secretary General Mark Rutte in the Oval Office, Trump warned, "We're going to be doing very severe tariffs" if a ceasefire agreement on Ukraine is not reached within 50 days.

US Commerce Secretary Howard Lutnick clarified later that Trump actually meant "economic sanctions" when he threatened "secondary tariffs" against Russia, The Washington Times reported.

Trump also told Rutte that the United States will send weapons to Ukraine through NATO, including Patriot missile systems, with deliveries starting soon.

In a post on X following a phone call with Trump, Ukrainian President Volodymyr Zelensky expressed gratitude for Trump's "willingness to support Ukraine" and hailed their strong relationship.

This is not the first time Trump has expressed disappointment with Putin over the Ukraine crisis, despite claiming he has a good relationship with the Russian leader. In early July, after a phone conversation with Putin, Trump told reporters, "I didn't make any progress with him today at all," adding, "I'm not happy about that."

READ MORE: Kyiv says US resuming aid for Ukraine

Trump, who promised during his campaign to end the conflict in Ukraine within 24 hours, has held several conversations with Putin since taking office. However, his efforts to pressure the Russian leader have yet to yield a ceasefire.

Ukrainian President Volodymyr Zelensky said on social media that he spoke with Trump and "it was a very good conversation."

"Thank you for the willingness to support Ukraine and to continue working together to stop the killings and establish a lasting and just peace," said the Ukrainian president.

The Russian Foreign Ministry warned that supplying longer-range missiles will make Europe a participant in aggression, according to Tass news agency. Kremlin spokesperson Dmitry Peskov accused Washington of escalating the conflict but did not announce specific countermeasures.

Deputy Chairman of the Russian Security Council Dmitry Medvedev on Tuesday called Trump's statements against Russia a "theatrical ultimatum" and the country "didn't care."

"Trump issued a theatrical ultimatum to the Kremlin. The world shuddered, expecting the consequences. Belligerent Europe was disappointed. Russia didn't care," Medvedev wrote on X.

ALSO READ: US halts military aid to Ukraine amid low US stockpiles concerns

German Defense Minister Boris Pistorius said Berlin will coordinate with allies on deliveries. However, some German lawmakers expressed concern that sending Taurus cruise missiles could provoke Moscow, reported German newspaper Die Welt.

The plan could force Russia to reconsider the security of its rear areas, since assets previously considered safe may now be at risk, RAND Corporation military analyst Dara Massicot told the Washington Post.