President Donald J. Trump suggested that he was powerless to control Russian President Vladimir V. Putin ahead of a planned meeting in Alaska, saying he could not convince the Russians to stop killing Ukrainian civilians or hacking American court records.

Mr. Trump did warn of "severe consequences" if Mr. Putin did not agree to abandon his grueling invasion of Ukraine during their discussion, scheduled to be held at Joint Base Elmendorf-Richardson in Anchorage.

But Mr. Trump was dismissive when asked to address matters of national security and the horrors of war, raising questions about whether he has the leverage or the will to convince Mr. Putin to end the invasion.

Asked whether he could convince Mr. Putin to stop targeting civilians, Mr. Trump said that it was a discussion he had already had with Mr. Putin.

Russian forces have pounded Ukrainians with drones and missiles, sending civilians scrambling for shelter.

Mr. Trump and Mr. Putin have spoken at least five times since Mr. Trump was sworn in for a second term in January, and Russian forces have pushed forward all the while.