Upvote:0
Any use or disclosure of your country-of-origin citizenship (Gambia) is a very very bad idea, and you should not do that without first speaking to a US attorney versed in immigration and asylum matters.
The reason is that asylum was granted based on your convincing the US authorities that you were at risk in Gambia. Using your Gambian passport or stating publicly your Gambian citizenship, however, is an acknowledgment of the authority of Gambia over you, and your submitting to its protection.
This, in turn, will be seen by the US authorities as your statement that you no longer are in danger from Gambia. You run the real and significant risk that your asylee status and green card will be revoked. You can read more in this thread. Even worse, if you have trouble overseas, you might be deported not to the US but instead to Gambia.
Talk to a lawyer in the US before going any further with this.
Upvote:2
On the site below, Travel document as Passport type is being offered.
So check if on the application if there is also a Passport type field. [answered: there is none]
Use the number of the Travel document for the Passport Number and select your nationality as stated in the Travel document.
Since you must submit the Travel document with the visa application, they will see what type of document it is.
Do I need a Visa? | CancillerΓa
returns
VISITOR VISA - TYPE V: for the foreigner wishing to visit Colombia once or several times or to stay temporarily in the country without this being permanent.