The admission that the Trump Organization was working secretly—colluding, one might say—with the Russian government on a business deal late into the campaign and that Trump knew about this activity led many observers, including those quoted above, to treat this latest plea as the turning point for Special Counsel Robert Mueller’s investigation.

But the underlying metaphors are wrong. There is no sudden bend in the path of the investigation. There is no house of cards. The dominoes will not fall if gently tipped. The administration is not going to come crashing down in response to any single day’s events. The architecture of Trump’s power is more robust than that.

Joshua Zoffer and Niall Ferguson: Mueller and a blue House could bring down Trump

We need to stop thinking of it as a fragile structure waiting for the right poke to fall in on itself. Think instead of the myriad investigations and legal proceedings surrounding the president as a multi-front siege on a walled city that is, in fact, relatively well fortified.

Siege warfare is not a matter of striking precisely the correct blow at the correct moment at a particular stone in the wall. It is a campaign of degradation over a substantial period of time. While those inside the fortified city may rely only on the strength of their walls and their stored resources, the attackers can take their time. Volleys of projectiles—arrows or trebuchets—pepper the city walls and those atop them, while the strength of the defending army diminishes as soldiers slip away and food dwindles. Moreover, active conflict is an episodic, not a constant, feature of siege warfare; the enemy army can encamp outside the walled city and blockade it without firing a shot. Over time, the walls and defending forces become degraded to such a degree that the invaders are able to scale the walls and sack the city.

No, Mueller and his forces are not a Mongol horde, but the Trump White House is very much under siege.

Mueller’s army isn’t the only force encircling Trump’s fortress, but it is the largest and most active force, and it actually has several distinct encampments. One contingent of Mueller’s forces is charged with investigating efforts by the Russian government to interfere with the 2016 election. In this capacity, the special counsel’s office has indicted individuals associated with the Internet Research Agency, a Russian troll farm that has spread disinformation and propaganda on social media. His office also indicted 13 members of the Russian military intelligence organization, the GRU, in connection with deliberately hacking into the Democratic National Committee server and passing the fruits of that hack to WikiLeaks “to interfere with the 2016 U.S. presidential election.”

Read: Is WikiLeaks a Russian front?

The immediate threat this particular force poses to the castle right now involves its evident interest in Roger Stone and the group of people around him. The GRU indictment does not name Stone, but he has publicly admitted that he is the person referred to in the indictment “who was in regular contact with senior members of the presidential campaign of Donald J. Trump” and who corresponded with a fake hacktivist persona used by the Russians.