The US Navy has taken delivery of the 13th Virginia-class submarine, Pre-Commissioning Unit (PCU) Illinois (SSN 786), ahead of the initial contract schedule.

The $2.7bn SSN-786 is the ninth consecutive Virginia-class submarine to be delivered early to the navy.

General Dynamics Electric Boat division has delivered the nuclear-powered attack submarine four days ahead of schedule and within budget, SEAPOWER Magazine reported.

"Illinois' delivery continues the programme's success of delivering Virginia-class submarines ahead of schedule and within budget."

US Navy Virginia-class programme manager captain Michael J Stevens said: "Illinois' delivery continues the programme's success of delivering Virginia-class submarines ahead of schedule and within budget.

"Our plan is to have Illinois out on operations next year, going from construction start to mission-ready in just over six years."

Designed to operate in littorals and deep waters, the Virginia-class submarines are capable of conducting anti-submarine warfare; anti-surface ship warfare; strike warfare; special operation forces support; intelligence, surveillance, and reconnaissance; irregular warfare; and mine warfare missions.

The submarine supports five of the six maritime strategy core capabilities, which include sea control, power projection, forward presence, maritime security, and deterrence.

Expected to enter service in October this year, Illinois is the third of eight Virginia-class Block III submarines.

The Block III submarines have a redesigned bow, which replaces 12 individual launch tubes with two large-diameter Virginia Payload Tubes, each capable of launching six Tomahawk cruise missiles.

This, among other design changes, reduced the submarines' acquisition cost while maintaining their warfighting capabilities, the US Navy said in a statement.

Image: An artist rendering of the Virginia-class submarine USS Illinois (SSN 786). Photo: courtesy of US Navy photo illustration by Stan Bailey/Released.