India, Oct. 28 -- Three of UK's four nuclear submarines are out at sea as per multiple reports. The reason for these nuclear deterrent subs' deployment is not immediately clear but it is understood that at least one of the vessels will be armed with nuclear warheads, and be on routine patrol.

The Times reported on the activity first and spoke to a source who described it as "unusual" without explaining why. Meanwhile, an expert told Sky News that one of the Vanguard-class submarines would likely be working up to take over the patrol, and the third could be undergoing sea trials.

This "unusual" deployment of most of UK's fleet suggests an improvement in availability where the Royal Navy's submarine service has run into problems in recent...