At the center of the House impeachment inquiry into President Trump's Ukraine dealings is the nearly $400 million in congressionally allocated security aid that Trump ordered withheld from Kyiv for still-unclear reasons. House Democrats are investigating whether Trump was using the $250 million in Pentagon funds or $141 million in State Department aid as leverage to force Ukraine's president to announce an investigation of former Vice President Joe Biden, a leading Democratic presidential candidate.

Trump's Republican allies argue that there was no quid pro quo — aid for investigations — because the Trump administration lifted its hold on the money Sept. 11. "Ukraine in fact received the aid and there was no investigation into the Bidens," Rep. Elise Stefanik (R-N.Y.) said during Tuesday's impeachment hearings.

"But $35.2 million — earmarked for grenade launchers, secure communications, and naval combat craft — has not left the U.S. Treasury," the Los Angeles Times reported Tuesday, citing Pentagon spending documents and lawmakers. And the Pentagon isn't saying why it has not sent Ukraine the money. Pentagon spokeswoman Lt. Col. Carla Gleason told the Times only that the remaining $35 million will be disbursed "over the next several weeks."

Democratic lawmakers say the Defense Department is stonewalling them, too. "We've raised the question and we have not received an answer," said Rep. John Garamendi (D-Calif.), chair of the House Armed Services Committee's readiness subcommittee. "We're going to have to find out why." Senate Democrats wrote Defense Secretary Mark Esper on Monday arguing that "speeding the delivery of this critical aid, which Congress specifically appropriated to improve the security of Ukraine, is important to affirm our commitment to Ukraine in the wake of the chaotic, undisciplined, and deeply concerning approach the administration has taken toward our important partner."

Congress approved the funds a year ago, but because the White House kept them on ice until right before the fiscal year ended Sept. 30, lawmakers gave the Pentagon another year to spend the $250 million. Peter Weber