Sorry for shit format, at work and trying to piece this together on the fly.
Pompeo tweet with .gov link ending in xA89E
Very next tweet includes the word key and Pennsylvania
Roman numeral x = 10, other letters capitalized A1B2C3... 10 + 1 + 89 + 5 = 105
Drop 105 Pennsylvania is the keystone state; search drops for keystone to find these lines -
Be [p]repared. Ope[r]ations underway. Operators [a]ctive. Graphic is essential. Find the ke[y]stone. Help appreciated, further research needed??
lowercase x preceding a set of numbers within 0-9A-F inclusive USUALLY represents a hexadecimal (base 16) number
hex A89E to decimal is 43,166
More straight forward explanation though that doesn't seem significant.
I don't have time, nor the skill to truly dig, but I deal with Hex a lot.
If you want a straight conversion and not to decimal: xA89E could also be 10.8.9.14
And just for whatevers, octal conversion is 124,236
All references for Hex xA89E in geek world:
https://www.fileformat.info/info/unicode/char/a893/index.htm