Following this morning's tweet-announcement by the president of a ban on trans people serving in the military — something that could effect over 2,000 active-duty troops — an "emergency protest" has been announced in the Castro beginning at 6 p.m. Wednesday, at Harvey Milk Plaza.

"Please come to this emergency protest to show [Trump's] administration and the world that San Francisco stands with the transgender community," reads the Facebook announcement by a group called The Resistance. Over 500 have already said they are attending and over 1,100 others are "interested" just a couple of hours after the event was posted.

Earlier we saw some swift Twitter reaction to the president's snap decision, including from House Minority Leader Nancy Pelosi and recently released-from-prison (but still active-duty) service member Chelsea Manning.

Politico surmises that President Trump's decision to announce the ban, without consulting even his own defense secretary (it seems), came as a result of a last-ditch effort to save a spending bill in the House that includes funding for one of Trump's key campaign promises: the wall along the Mexican border. Fighting among defense hawks and the Pentagon over funding for sex-reassignment surgery for military personnel threatened to derail the bill, and this apparently spurred Trump's early morning tweets.

The president had, allegedly, always planned to roll back some of the Obama-era protections for trans people in the military, but an outright ban had not previously been on the table, according to the New York Times.

Related: Chelsea Manning, Nancy Pelosi And Others React To Proposed Trans Military Ban