Offering the first official glimpse of the parameters of Trump's "wall" along the US-Mexican border, an internal Department of Homeland Security report seen by Reuters reveals that the structure would be a series of fences and walls that would cost as much as $21.6 billion, and take some three and a half years to construct. The proposed cost is much higher than the $12-billion figure cited by Trump during his campaign and also higher than the $15 billion cited by Republican House Speaker Paul Ryan and Senate Majority Leader Mitch McConnell. This latest leaked report is expected to be presented to DHS Secretary John Kelly in the coming days, although the administration will not necessarily take the actions it recommends.

Allegedly the new border wall will be completed in three phases, with the first phase covering only 26 miles around the easily accessible areas surrounding San Diego, CA and El Paso, Texas. Among other things, starting with the easiest and most accessible sections of the wall will allow President Trump to declare an early victory on a key campaign promise.

Phase two of the project would cover another 151 miles around other large border cities while phase three would effectively seal off the border.

The plan lays out what it would take to seal the border in three phases of construction of fences and walls covering just over 1,250 miles (2,000 km) by the end of 2020. With 654 miles (1,046 km) of the border already fortified, the new construction would extend almost the length of the entire border. The report said the first phase would be the smallest, targeting sections covering 26 miles (42 km) near San Diego, California; El Paso, Texas; and in Texas's Rio Grande Valley. The second phase of construction proposed in the report would cover 151 miles (242 km) of border in and around the Rio Grande Valley; Laredo, Texas; Tucson, Arizona; El Paso, Texas and Big Bend, Texas. The third phase would cover an unspecified 1,080 miles (1,728 km), essentially sealing off the entire U.S.-Mexico border.

Of course, getting funding for the wall is likely one of the easier challenges the President will face from Democrats who will be all too eager to throw up every roadblock possible to thwart it's construction. A source familiar with the plans told Reuters that DHS will almost certainly face environment challenges and may have to go to court to seek eminent domain in order to acquire some of the private land needed to cover the final and most ambitious phase of construction.

The report assumes DHS would get funding from Congress by April or May, giving the department sufficient time to secure contractors and begin construction by September. Several U.S. congressional delegations are visiting the border this month to assess funding needs, according to several people familiar with the travel plans. The report shows the U.S. government has begun seeking waivers to address environmental laws on building in some areas. It also shows the government has begun working with existing contractors and planning steel purchases for the project. In addition to seeking eminent domain and environmental waivers, the U.S. government would also have to meet the requirements of the International Boundary and Water Commission, a U.S.-Mexico pact over shared waters. The report estimated that agreement alone could bring the cost from $11 million per mile to $15 million per mile in one area.

DHS and White House representatives refused to comment on the alleged report saying they do "not comment on or confirm the potential existence of pre-decisional, deliberative documents" and that it would be "premature" to comment on a report that has not officially been presented to the president.

And while Reuters notes fairly extensive details about cost estimates and staging of construction, there is no mention of how/if/when U.S. taxpayers will be reimbursed the $22 billion price tag by Mexico. We're awaiting official confirmation from Vicente Fox on when he expects Mexico to cut a check.