Justice Secretary Humza Yousaf said the navy will not be deployed to Scottish waters unless the chief constable requests it to be “GUNBOAT diplomacy will not be welcome in Scottish waters,” the Justice Secretary has said after the UK put the Royal Navy on standby in case of a No-Deal Brexit. Humza Yousaf tweeted this morning that the UK Government had confirmed with him that the navy won’t be deployed unless the chief constable requests so. The Ministry of Defence has confirmed that four navy boats are prepared to patrol British fishing waters if the UK leaves the EU with no deal agreed.