A rule for a citizen from another country mentions that if its citizen gets citizenship of another country, they will automatically lose the citizenship. So, would it be correct to write that I only have US citizenship in the 86 forms?
No one but you can answer your citizenship question. Many people have dual or multiple citizenship. It is not uncommon. Only you know your situation.
but a quick google search helps…
It’s best to do your homework and research your situation.
Dual citizenship is not necessarily automatic and in most cases requires some effort to maintain.
There are several origin countries that won’t recognize the fact that their citizen has obtained US naturalization.
Most origin countries will want their citizens to maintain the origin citizenship via passport from the origin country or national ID. There may be fees, taxes, and other financial requirements involved.
Outside of US government security clearance requirements, holding dual citizenship with an origin country and US naturalization isn’t problematic. However, when a US government security clearance is needed the citizen involved has extra responsibilities to address. The clearance process will need to review: the reason for holding dual citizenship, the steps taken to obtain/maintain citizenship outside of the US, which citizenship holds overall allegiance, how each citizenship is being used (benefits, passport services, finances, travel perks….), among other things.
All of that being said, there are problematic origin countries (Iran, Iraq, China….) that cause red flags to fly when coupled with US naturalization. While it would be better to officially renounce citizenship with high risk countries, many of those locations will not accept renouncing - more investigation is required for those situations.
No matter what your origin country is, anyone claiming dual citizenship -and wants to be issued and maintain a US security clearance- should be aware of their associated citizenship responsibilities and take the proper precautions to follow expectations involved (ie: proper passport use, avoid allegiance issues, reporting citizenship involvement/activities…)
The US Department of State may be your best location to gain information regarding dual citizenship.