Daijr,

The use of "minister" to label diplomats is very old-fashioned now, and while the JEs I have consulted (still) use it, I think it is best pushed to the end. I think the example quoted demonstrates that "deputy chief of mission" is one of the job titles encompassed by 公使, but it's far from being the only one; it also covers various attachés, charge d'affaires, etc.

@@ -17,0 +18,2 @@
+<gloss>envoy</gloss>
+<gloss>diplomat below the rank of ambassador (e.g. deputy chief of mission, charge d'affaires)</gloss>
@@ -19,2 +20,0 @@
-<gloss>envoy</gloss>
-<gloss>deputy chief of mission</gloss>

"envoy" is in GG5
.
Regarding "deputy chief of mission", here are extracts from two recent articles about the same incident (vandalism of copies of Anne Frank's diary in Tokyo municipal libraries):
.
"Israeli embassy's Deputy Chief of Mission Peleg Lewi (C) and Jewish community of Japan president Philip Rosenfeld (L) smile with Ryo Tanaka (R) Mayor of Suginami ward during a ceremony to donate 300 copies of Anne Frank's 'Diary of a Young Girl' in Tokyo on February 27, 2014. "
.
この事件を知った駐日イスラエル大使館のペレグ・レヴィ（Peleg Lewi）公使と、日本ユダヤ教団のフィリップ・R・ローゼンフェルド（Phirip R Rosenfeld）会長は2月27日、112冊と被害が最も多かった自治体である杉並区を訪れ、田中良区長に被害にあった自治体すべてに300冊の新たな本を寄贈することを約束した。
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http://en.wikipedia.org/wiki/Deputy_Chief_of_Mission
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Genius WaEi notes that 公使 is a diplomatic position ranking below ambassador.

@@ -18,0 +19,2 @@
+<gloss>envoy</gloss>
+<gloss>deputy chief of mission</gloss>