The front-story is that Mitch McConnell organized his Decepticon coalition to warn President Trump not to withdraw U.S. troops from Afghanistan and Syria.  However, the more true back-story is McConnell warning President Trump that he has assembled his impeachment coalition.
The Senate passed a “sense of the senate” resolution today demanding that President Trump keep troops actively engaged in perpetual war.
The resolution passed the cloture vote by a margin of 68 to 23.  When you understand the background of the ‘Senate Cloture Scheme’ (see Trade Promotion Authority and TPP), today’s Senate vote essentially highlights the Decepticon caucus. [The Big Club]
Here’s how they voted:

(link)

Those who have followed Mitch McConnell for a long time will immediately notice the republican names in his coalition.  They are the identical recipients of direct payments made by U.S. Chamber of Commerce President Tom Donohue.
Notice also that Senator McConnell timed his rebuke against President Trump to take place just prior to the State of the Union address.

In addition to demanding perpetual war (and all the financial benefits therein), the republican vote is a signal to the republican President that he will not be allowed to defy the will of the Big Club.
In many ways this is also the deep swamp protecting themselves from the structural reform which would happen as a consequence of President Trump draining the swamp. Remember, the 2016/2017 Intelligence Community (CIA, DOJ, FBI) operation against Donald Trump was NOT exclusively supported by Democrats.  Just like the Republican apparatus supported the DOJ/IRS targeting of the Tea Party, the Republican wing of the same apparatus also supported the ‘Spygate’ agenda against Donald Trump.
With this vote McConnell is warning President Trump he has enough votes to support the Pelosi/Schumer impeachment agenda; if needed.