Learn English – Is ‘Jap’ still considered an ethnic slur

Jap is still considered an offensive term in the US. From personal experience, I remember an afternoon in public school where a classmate used the word "Jap" and was scolded by the teacher. The well-cited Wikipedia entry on the term supports this:

Today it is generally regarded as an ethnic slur among Japanese minority populations in other countries, although English-speaking countries differ in the degree to which they consider the term offensive. In the United States, Japanese Americans have come to find the term controversial or offensive, even when used as an abbreviation.

Additionally, there's evidence that the term can be controversial in the UK specifically. Again from the Wikipedia:

In 2011, following the term's offhand use in a March 26 article appearing in The Spectator ("white-coated Jap bloke"), the Minister of the Japanese Embassy in London protested that "most Japanese people find the word ‘Jap’ offensive, irrespective of the circumstances in which it is used."

Perhaps it goes without saying, but the term is considered offensive due to its usage by Americans during WWII. (Before the war it was not considered offensive.) Once more from the Wikipedia entry on the term:

Later popularized during World War II to describe those of Japanese descent, "Jap" was then commonly used in newspaper headlines to refer to the Japanese and Imperial Japan. "Jap" became a derogatory term during the war, more so than "Nip." Veteran and author Paul Fussell explains the usefulness of the word during the war for creating effective propaganda by saying that "Japs" "was a brisk monosyllable handy for slogans like 'Rap the Jap' or 'Let's Blast the Jap Clean Off the Map.'"