According to an announcement on the official website of Strike Witches
, a new OVA and TV series will be released. The OVA has been tentatively titled "Operation Victory Arrow (O.V.A.)." Information provided on the website hints at something named "Tactics of Vanadis Attack" in regard to the new TV series, but schedule, staff, and cast details have not yet been revealed.
The Strike Witches franchise consists of anime, manga, novels, essays, and art books. On the anime side, there was the first season made by Gonzo (aired in 2008), a second season made by AIC Spirits (aired in 2010), and a movie (also by AIC) which premiered in 2012.
Official anime website: http://s-witch.cute.or.jp/
Source: Official Strike Witches website
Story by ZorroGuevara
Strike Witches: Operation Victory Arrow