US naval ship activities in Irish waters cause concern for Defence Force officials

Virginia Ann is classified as offshore supply ship but is understood to be capable of advanced subsurface operations such as deployment of deep-sea divers

Virginia Ann

An advanced US naval ship which has been operating in Irish-controlled waters for four months with its transmitter turned off is causing concern among Irish defence officials.

The Virginia Ann, which is fitted with equipment capable of subsea operations, left Cork on Thursday morning, where it was being resupplied, and is currently sailing west.

The ship is operated by the US Naval Facilities Engineering and Expeditionary Warfare Centre or Navfac-EXWC, a section of the US navy responsible for maintenance and installation of subsurface infrastructure, including undersea surveillance systems.

Built in 2015, the Virginia Ann is officially classified as an offshore supply ship but it is understood to be capable of advanced subsurface operations, including the deployment of deep-sea divers.


In 2020, it was purchased by Navfac-EXWC which, according to its website, oversees “seafloor engineering, moorings, shore-based hyperbaric facilities, and underwater cable structures”.

Since January, the Virginia Ann has been sailing back and forward between the waters off Co Cork and the very southern tip of the UK, mostly with its Automatic Identification System (AIS) turned off.

Vessels, particularly military vessels, often turn off their AIS when attempting to conceal their movements.

Maintaining an AIS signal is considered best practice from a safety point of view. However it is not generally a legal requirement and there are several reasons ships may not display one.

The task of the Virginia Ann remains unclear but its lengthy and sometimes hidden presence in the Irish Exclusive Economic Zone (EEZ) has caused some concern among Irish military officials.

The Irish Times asked a naval expert to examine a photo of the ship taken in Cork this week. They said the visible equipment indicated it was involved in manned diving operations and possibly subsea cable surveys or repairs.

“It’s not that it poses a national security threat necessarily. It’s more that it shows our inability to monitor what’s happening in our own backyard, whether it’s the Russians or Americans or whoever,” said one military source.

Security sources said the ship may be involved in efforts to upgrade a cold war-era underwater surveillance system used to detect Russian submarines.

This “Sound Surveillance System” (Sosus) consisted of underwater hydrophones placed at strategic chokepoints to alert the US any time a Russian sub entered the North Atlantic. The previously classified system is currently undergoing a replacement programme.

The recent activity of the Virginia Ann is also “a neat illustration of the extent to which Irish waters are a hotbed for these types of geopolitical games”, a military source said.

Russian military ships, or ships connected to the Russia government, have become frequent visitors to Irish waters in recent years, prompting concern among some experts that they are mapping or interfering with subsea cables off the Irish west coast.

On Thursday, Taoiseach Leo Varadkar said Ireland was open to EU or Nato co-operation to protect its critical undersea infrastructure.

The Virgina Ann left Cobh in Co Cork on Thursday following a brief visit and was heading west last night. The Department of Foreign Affairs said it visited Cobh “to change crew and receive supplies” and that permission had been sought from the US embassy.

“Visits from foreign naval vessels are a long-standing and common practice in Ireland and worldwide and it is therefore normal and welcome for foreign naval vessels to visit Irish ports,” a spokesman said.

The department did not respond to queries about the ship’s activity in the Irish EEZ. It said any vessel transiting the EEZ must do so “in compliance with international law”.

Neither Navfac-EXWC or the US department of defence responded to queries.

Conor Gallagher

Conor Gallagher

Conor Gallagher is Crime and Security Correspondent of The Irish Times