The Asia Reassurance Initiative Act was a Trump administration initiative.
You can find federal statutes at
https://uscode.house.gov/browse.xhtml
A search for the “Asia Reassurance Initiative Act” (Pub. L. 115-409, Dec. 31, 2018, 132 Stat. 5387) leads ultimately here:
https://uscode.house.gov/statviewer.htm?volume=132&page=5387
You can page through its 24 pages, which end at page 5411.
I’m not sure what it is or does.
Update: a quick scan of the text of the act, including the authorization clause, which describes the use of appropriations, suggests that the Asia Reassurance Initiative Act of 2018 acts as a vehicle for a wide variety of vague spending programs in and near Asia, ostensibly diplomatic efforts to advance the interests and foreign policies of the United States of America. In other words, this money probably will go to someone in or near Asia for some undisclosed purpose. I cannot determine whether this money is just general freewheeling excessive spending on just any account to pay bureaucrats, a purely corrupt initiative that some Congressperson will reveal in secret to some bureaucrat in the Department of State, or something else entirely, benign or nefarious.