As said by other comments and answers the main issues of eating with fork and knife as in western culture are: The (quasi) prohibition of eating with the left hand and the other issue is the imitation of non-Muslims.
AFAIK or at least I've been told american people have the fork in the right hand so this way to eat would at least eliminate the first possible issue. Note that if somebody is injured or can't eat with the right hand for reasonable reasons (what ever that might mean) it is permissible for him/her to eat with the left hand.
For the second issue especially I found many modern or contemporary scholars having no consensus for example on Islamweb the muftis seem to follow the view that using tools to eat is rather frowned upon, but one could use them for necessary acts, for example cutting with a knife using a spoon to eat supper and so on, while salafi scholars as presented by many different posts on a similar question in this thread (Arabic) show that some allow it some prohibit it for one of the above reasons quoted above.
For example sheikh al-Fadil as-Su'aidan الشيخ الفاضل السعيدان consider it as prohibited because of the imitation of the kuffar (disbelievers), ibn Jabreen however say it is not an imitation of kuffar as they are not the only one to do it, al-Labani at least considered using a spoon as allowed (even if it has no backup in sunnah). While the saudi fatwa council declared it as allowed and not at all an imitation of non-Muslims as you may read [here (islamqa #112005).
While in my search i found the shi'a marji' Sistani quoting:
25 - Do not to cut bread with a knife ٢٥ ـ ان لا يقطع الخبز بالسكين.
among the etiquette of eating and drinking.
On islamweb (based on this Arabic fatwa #51496) they also added some reasons for the dislike of eating with a spoon (and one could follow by analogy that this is the case for a fork two):
- opposition to the way of the salaf!
- because these tools enter the mouth and leave it (when eating by hand only, only the bite enters the mouth).
- there's some kind of luxury and comfort in eating this way.
But they consider eating with a spoon as allowed, however the best way would be eating with the (right) hand. As this is the way of the Prophet () and the salaf.