Yes, the securities holding in US Domestic Corp will be subject to estate tax.
A non-resident alien is subject to U.S. estate tax on their
taxable estate assets situated in the U.S. (IRC §2101(a), 2106(a)).
For U.S. estate tax, both stock of a U.S. corporation (IRC
§2104) and U.S. real estate (Treas Reg §20.2104-1(a)91)) are
"situated" in the U.S.
See link to Sec 2104
and IRS link for your reference-
Let me know if you have any question.
Please note: This advice is provided with the understanding that all the relevant facts have been provided by you. Any change in facts might affect the advice given and hence may not be relied on in such cases. Nothing contained in this reply was intended or written to be used, can be used by any taxpayer, or may be relied upon or used by any taxpayer for the purposes of avoiding penalties that may be imposed on the taxpayer under the Internal Revenue Code of 1986, as amended.