The entire Donald Trump-Kim Jong Un summit looks like it may have been a costly mistake.

Not only was it it bad for Trump’s reputation at home and abroad, the meeting in Vietnam cost US taxpayers at least $6 million, according to a Quartz analysis of government spending reports and Air Force One operating costs.

That figure likely underestimates significantly the total expense of the presidential trip to Hanoi, because it doesn’t include the cost of flying advance teams to Asia in order to plan and to scout meeting locations, the extra security costs to protect the White House team, or on-the-ground costs during two refueling stops for Air Force One.

The expenditures reported by the government so far are only a partial picture, as filings are often made weeks, sometimes months, after expenses are incurred. Some filings contain more detail than others—there’s a $160,000 Secret Service expenditure that’s classified just as “CREDENTIALING VIETNAM KIM JUNG UN (sic).” Others are linked to the summit by date, location, or agency.

Here’s a bare minimum on what setting up the summit cost US taxpayers, by category:

Flight costs: At least $4.28 million

Air Force One departed Andrews Air Force Base in Maryland at 12:30pm US Eastern time on Feb. 25, stopped for two one-hour refueling stops in the UK and Qatar, and arrived in Hanoi at 9:30am ET on Feb. 26, for a total flight time of 15 hours.

Flying Air Force One from Washington to Hanoi cost $2.14 million each way, based on the Defense Department’s hourly operating rate of $142,380 for the presidential plane—a round-trip cost of $4.28 million. The Marine One helicopters normally used to fly Trump from the White House to Andrews weren’t used on departure because it was too windy. The president and his team traveled by motorcade. If they’re used on his return, as expected, that’s another $14,406.

Lodging: About $1.2 million

The US contingent rented an unknown number of hotel rooms, as well as conference rooms and meeting spaces, for a total of roughly $1.2 million.

Bitexco Hotel Management Company (JW Marriott Hanoi) $17,107

Bitexco Hotel Management Company (JW Marriott Hanoi) $21,455

Bitexco Hotel Management (JW Marriott Hanoi), $25,346

Bitexco Hotel Management Company (JW Marriott Hanoi) $28,875

Bitexco Hotel Management Company (JW Marriott Hanoi) $37,514

Bitexco Hotel Management Company (JW Marriott Hanoi) $38,877

Bitexco Hotel Management Company (JW Marriott Hanoi) $110,852

Melia Hanoi, conference space $157,309

Metropole Hanoi, conference room $12,943

Metropole Hanoi, conference setup $12,975

Metropole Hanoi, lodging $13,787

Metropole Hanoi, conference rental $38,581

Metropole Hanoi, USSS funded lodging $84,557

Metropole Hanoi, conference rental $121,542

Metropole Hanoi, conference rental $142,943

Metropole Hanoi, lodging (funded by USSS) $186,059

Misc. foreign awardees, conference space $15,151

Misc. foreign awardees, conference space $61,693

Misc. foreign awardees, paid by State Department diplomatic security $84,138

Misc. foreign awardees (listed as “LODGING ROOMS”) $15,226

Misc. foreign awardees (listed under the US government classification code for hotels), $84,138

Misc. foreign awardees (“HOTELS”) $44,618

Misc. foreign awardees (“HOTELS”) $159,784

Transportation: Approximately $224,000

The Trump team’s transport costs include a $14,000 charge for “hangar rental,” presumably for Air Force One.

Hangar rental, $14,385

Misc. foreign awardees (listed as “TRANSPORTATION/TRAVEL AGENCIES”), $24,828

Misc. foreign awardees (“TRANSPORTATION/TRAVEL AGENCIES”), $52,507

Red River Travel (a Hanoi limousine service), $16,348

Red River Travel, $54,736

Red River Travel, $61,259

Miscellaneous: Roughly $300,000

Internet connections, special lighting, drapes, and credentialing services added up to about $300,000.