President Donald Trump dismissed recent reports suggesting that the cost of constructing a wall on the U.S.-Mexican border could be nearly double what he anticipates, promising that when he begins negotiations the “price will come way down.”

A Homeland Security report seen by Reuters on Friday stated the cost of the wall could be as much as $21.6 billion, considerably more than the $12 billion figure cited by Donald Trump during the campaign.

The report also found that the wall, which will secure over 1,250 miles of the southern border between the United States and Mexico, could take three and a half years to build, meaning it would be completed at the end of 2020, potentially when Trump is out of office.

The current Secretary of the Department of Homeland Security (DHS), retired Marine General John Kelly, previously said the construction of the wall could be completed in under two years.

However, Trump dismissed claims of an inflated cost, writing in a tweet that “I am reading that the great border WALL will cost more than the government originally thought, but I have not gotten involved in the design or negotiations yet.”

“When I do, just like the F-35 FigherJet or the Air Force One Program, price will come WAY DOWN!”, he continued.

I am reading that the great border WALL will cost more than the government originally thought, but I have not gotten involved in the….. — Donald J. Trump (@realDonaldTrump) February 11, 2017

…design or negotiations yet. When I do, just like with the F-35 FighterJet or the Air Force One Program, price will come WAY DOWN! — Donald J. Trump (@realDonaldTrump) February 11, 2017

Before his inauguration, Trump received assurances from the CEO of the aerospace defense company Lockheed Martin, Marillyn Hewson, that she would significantly reduce the high cost of F-35 Joint Strike Fighter program.

Following a meeting in Florida, Boeing CEO Dennis Muilenburg also gave Trump his “personal commitment” in making the Air Force One Program more affordable.

A key campaign pledge of Trump’s concerning the construction of the wall was that Mexico would pay for it. Last month, Trump said Mexico would “pay later” for the wall, after its construction.

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