New revelations come almost by the minute in the Trump-Russia affair. The White House moves into full-defense mode. The Trump agenda stalls on Capitol Hill.

A reasonable observer might conclude that is all that is happening in the Trump administration. But even as those troubles fill news sites and cable TV, administration officials are quietly moving ahead on one of the president’s top campaign promises: the construction of a wall on the U.S.-Mexico border. Although it hasn’t received much attention relative to the president’s many problems, extensive planning for the wall is under way, officials are evaluating specific proposals, sites are being studied, and yes, there is money available to get going.