WASHINGTON — President Donald Trump’s administration has told members of Congress it will not finish spending $400 million Congress has authorized for aid to Ukraine until fiscal year 2029, even as Kyiv runs critically low on weapons it needs to fend off Russian missile attacks.

In May, the Department of Defense sent a letter to lawmakers outlining its spending plan, a source familiar with the document said on Monday. Democrats and some of Trump’s fellow Republicans had criticized the Pentagon for sitting on aid for Kyiv, which members of both parties had backed last year.

Two months after the letter was sent, the funds still have not been disbursed or even obligated by being put on contract, the source said.

Congress has repeatedly complained about the slow pace of spending. The letter has not been previously reported.

Ukrainian President Volodymyr Zelenskyy is expected to meet with Trump at the White House on Tuesday, where he will keep pressing for urgently needed air defense capabilities and completing a drone deal with the U.S., a source familiar with the plans said.

After that meeting, he is expected to come to the U.S. Capitol to meet with the Senate. The House of Representatives is out of Washington for its summer recess.

Two sources said members of Congress were unhappy about the Pentagon’s timeline, which they consider unusually slow for an ongoing conflict.

The delivery timeline in the letter said the funds would be obligated during fiscal 2026, which ends on Sept. 30, and final delivery of all assistance is estimated in the year ending Sept. 30, 2029.

Trump’s second term ends on Jan. 20, 2029.

Trump has lately taken a positive tone toward Ukraine, signing off on a proposal to give a license for Ukraine to manufacture Patriot interceptor missiles and signaling that he would sign a Russia sanctions bill put forward by the late Republican Sen. Lindsey Graham, a close Trump ally in the Senate.

Zelenskyy will attend Graham’s funeral on Tuesday.

Graham’s sudden death this month raised the question of whether Trump’s recent tilt in favor of Kyiv would last without Graham’s advocacy, especially legislation to sanction Russia and military assistance for Ukraine.

The Pentagon did not immediately respond to a request for comment.