The Senate Appropriations Committee opened markup of a $94.1 billion Iran war supplemental Thursday morning, bolting an additional $4.7 billion for veterans’ mental health services and a Senate-confirmed inspector general for reconstruction onto a White House package that had arrived at $89.4 billion only six days earlier.

The chairman’s mark, circulated to members shortly after 9 a.m. and obtained by reporters at the dais, kept intact every line of the administration’s munitions-replenishment request, including the $34.2 billion earmarked for Patriot, THAAD, SM-6 and Tomahawk inventory. But it added a free-standing title creating a Special Inspector General for Iran and Iraq Reconstruction, modeled on the SIGAR office that oversaw the Afghanistan rebuild, with a five-year sunset and a $190 million standing budget drawn from administrative set-asides on the reconstruction account itself.

Chair Susan Collins of Maine, in a brief statement gaveling in the session, said the additions reflected “two lessons that this committee has refused to learn three times in a generation” — the costs borne by service members long after a war ends, and the costs borne by taxpayers when reconstruction dollars are pushed out the door without an independent watchdog. “There will not be a fourth time on my watch,” Collins said.

The markup arrived less than 16 hours after the Senate adopted the Kaine-Murphy war powers resolution 58-42, with five Republicans crossing the aisle, and only hours after Defense Secretary Pete Hegseth completed eight hours of closed and open testimony Wednesday before the Senate Armed Services Committee. The pace, three senior aides said Thursday morning, was deliberate. Collins and ranking member Patty Murray of Washington had spent the previous weekend agreeing on what one aide called “a Thursday vehicle” that would force the House to react before its Memorial Day recess targets slipped.

President Donald Trump, posting on Truth Social shortly after 10 a.m., called the Collins mark “a $5 BILLION ambush dressed up as oversight” and accused unnamed Republicans of “auditing a war they did not have the guts to vote against when it started.” He stopped short of issuing a veto threat against the underlying package, which White House officials have privately described as a must-pass priority before the fiscal-year-end munitions-procurement cycle locks in.

Vice President J.D. Vance, who walked the Senate side of the Capitol for nearly two hours Wednesday evening trying to head off the inspector general provision, told reporters outside the committee room Thursday that the administration’s objection was “structural, not personal.” Vance said an independent IG with subpoena authority would “freeze every reconstruction contract for nine months while the office stands itself up” and argued that existing Pentagon and State Department inspectors general were “more than equal” to the task.

Collins, asked about Vance’s argument during a brief recess, said the SIGIR experience in Iraq suggested otherwise. “We tried the existing-IG model in 2003,” she said. “We added SIGIR in 2004. The reason we added it is that the existing-IG model did not work, and the reason it did not work is that no single inspector general was structurally empowered to look across departments at a single reconstruction enterprise. The architecture of this war demands the same answer.”

Murray, in her opening remarks, called the package “the most consequential supplemental this committee has marked up since the COVID emergency” and pressed for two additional Democratic priorities: a binding reporting requirement on the post-ceasefire force posture, currently estimated by the Pentagon at roughly 24,000 personnel across the Gulf, and a $2.1 billion humanitarian set-aside for UN-channel assistance to Iranian civilians, which the administration’s transmittal had explicitly excluded. The chairman’s mark accepted the reporting requirement but held the humanitarian line below $1 billion.

Sen. Jack Reed of Rhode Island, the Armed Services ranking member who is not on Appropriations but appeared briefly in the committee room to confer with Murray, told reporters that Hegseth’s Wednesday testimony had “moved at least three votes on the IG question.” Hegseth had acknowledged under questioning that no single Defense Department office had yet been designated to oversee Iraq-side rebuild expenditures, a gap that aides said the administration had hoped to close internally before Congress acted.

“The fact pattern is doing more work than the politics,” said Maya Whitfield, a defense budget analyst at the Center for Strategic and Budgetary Assessments. “When the Pentagon cannot tell a committee which office is responsible for which dollar, the committee writes a new office into the statute. That is exactly what is happening here.”

House dynamics remained the harder problem. Speaker Mike Johnson, asked about the Collins mark in the Capitol Visitor Center, said the House would “look at what comes over” but warned that the IG provision would draw “serious resistance” from members worried about slow reconstruction contracts in their districts. Three House Republicans involved in defense industrial-base oversight said the bigger fight would be the $4.7 billion mental health add, which fiscal conservatives had begun characterizing as a non-emergency expense.

Rep. Theresa Holloway of Michigan, whose discharge petition to force a House vote on the war powers resolution sat at 188 signatures Thursday morning, said the supplemental fight had “opened a second front” for House Democrats. “The supplemental and the resolution are now the same political conversation,” Holloway said.

“The market read of this markup is that the war is fully a fiscal story now and no longer a security story,” said John Reilly, an analyst at Citi. “The question for the rest of the quarter is whether the House can produce a vehicle the Senate can accept without rewriting from scratch.”

The committee was expected to vote on the underlying package late Thursday evening, with floor consideration possible as early as Tuesday. Aides to Majority Leader John Thune said the leader would press for a brief amendment window and a vote by the end of the week of May 8 if the markup held together. Senate Democratic leadership said they would not block a procedural motion to proceed so long as the IG and reporting provisions survived intact.

Collins, gaveling the committee back into session shortly after noon, said she expected “long hours and short tempers” before the day was out. Officials said a joint statement from Collins and Murray would be issued at the close of business and that further floor steps would be announced once the committee’s vote tally was certified.