The Obama administration has spent at least $18.5 million to fly “unaccompanied children” caught crossing into the country illegally to locations inside the United States, according to newly obtained figures.

The numbers, shared with FoxNews.com by the Senate subcommittee on immigration, were provided by Immigration and Customs Enforcement in response to questions from Sen. Ted Cruz, R-Texas.

The numbers shed light on the extent of a program that has drawn scrutiny not just from lawmakers but the federal courts, amid concerns the U.S. government is effectively aiding smugglers.

“This shows how fundamentally flawed our approach to immigration enforcement has been in the Obama administration,” a Senate aide who has seen the questions to and answers from ICE Director Sarah Saldana told FoxNews.com.

The administration, which continues to grapple with waves of Central American migrants crossing the U.S.-Mexico border and has gone to great lengths to ensure the safety of minors, has defended the practice as appropriate.

But it comes with a cost.

The ICE figures show that from June 8, 2014 to Sept. 30, 2015, ICE spent $4.8 million on charter flights for the children (ICE could not provide figures before that period). From March 2009 to Sept. 30, 2015, ICE spent $13.7 million on commercial flights for unaccompanied minors utilizing funds appropriated to ICE.

In total, the cost reaches at least $18.5 million.

“This admission by ICE demonstrates that the United States is a party to countless conspiracies by illegal aliens to violate our immigration laws, by facilitating their illegal journey into the United States,” the Senate aide said.

Past accounts have said children have been flown from the U.S.-Mexico border to live with relatives, many of whom also are in the U.S. illegally.

But an ICE official told FoxNews.com on Friday they’re only transporting minors to facilities run by Health and Human Services’ Office of Refugee Resettlement, “as dictated by the Trafficking Victims Protection Reauthorization Act (TVPRA).”

The official added: “ICE does not transport children directly to parents or final destinations. We should also be clear that Congress has appropriated funds for the sole purpose of transporting these unaccompanied minors—that funding is separate from ICE’s enforcement and other funding. ICE is directed in this process by laws that Congress enacts and with funds they appropriate for that specific purpose.”

Separate questions to ICE posed by Republican Sen. Jeff Sessions’ office have yet to be answered.

In its written response to Cruz, ICE said it was unable to provide specific data regarding the number of unaccompanied children transported via commercial flight but that it is “in the process” of expanding its use of “contractor-conducted escorts in FY 2016 and will be able to provide more reliable data going forward.” ICE reported that between June 2014 and September 2015, about 10,000 children were transported by charter flights.

ICE has defended its role in transporting illegal immigrant children before -- namely, after U.S. District Judge Andrew Hanen complained in a Dec. 13, 2013 order that federal agents were intercepting human smugglers transporting children at the U.S.-Mexico border and then delivering those same children to their parents.

He called the practice "dangerous."

The comment prompted John Sandweg, ICE’s acting director at the time, to send an email to ICE employees defending the program and saying that the transportation of unaccompanied children by ICE personnel “is appropriate and legal.”

Despite its legality, the practice still isn’t sitting well with some.

“While ICE has spent millions of taxpayer dollars flying these young migrants to ... their chosen destination, it has not taken any action against their illegal alien family members who paid to have them smuggled to the United States,” the Senate source, who spoke on condition of anonymity, said.