The Government is considering the purchase of military jet aircraft that would have the capacity to intercept high-altitude planes and fully police Irish skies.
A new five-year Defence Forces investment strategy document has said that "future projects at a preplanning stage" include the potential for "air combat interceptors".
Such aircraft are designed to scramble quickly when there is a need to intercept unwelcome or unidentified planes which could include foreign military or hijacked airliners.
Although no decisions have been made on whether to pursue such high-end military hardware, it would require a major financial commitment potentially running into hundreds of millions of euro.
Expensive ground radar equipment would also be required to detect encroaching traffic in Irish airspace.
"Consideration of Air Combat Interceptors would be dependent on additional funding," the Defence Forces – Equipment Development Plan 2020-24 document, published on Friday, states.
Unlike most EU countries, Ireland does not have the capacity to fully secure its airspace by intercepting high-speed aircraft.
A Defence Forces spokesman said “such a capability is being kept under review, and is based on threat assessment, but budget has not been allocated for this at this time. Such an aircraft would be capable of policing all airborne craft in Irish sovereign airspace, particularly those that are fast moving.”
A spokeswoman for the Department of Defence said it is a "proposal that needs to be developed and scoped out".
“The assessment would consider the demands that may be made of such interceptors and the military capabilities it would be expected to be able to supply, together with the associated technical specification and capability requirements.
“This utility would have to be assessed against the significant investment of public funds, in respect of the initial investment and ongoing operational costs.”
The Air Corps has previously used both the De Havilland Vampire, a British jet fighter, and the French-designed Fouga Magister jet trainer aircraft. It also continues to operate the Ministerial Air Transport Service jet aircraft; however, the type of plane under consideration would represent a major upgrade in technology.
Earlier this year Maj Gen Ralph James, who retired as head of the Air Corps in 2015, said the State would need about 16 jet fighters with three crews each to implement a full air-defence capability.
He said each pilot would need up to 400 hours behind the controls of the jet before earning fast-response certification. A jet programme of this kind would likely cost well in excess of €1 billion.
Any such cost would impact the decision-making process – particularly given the cost to the State of the Covid-19 crisis.
In 2017, Fianna Fáil Senator Mark Daly noted in the Dáil that the public would "abhor spending €50 million or €100 million on jets that would have no real value in the long run".
However, the question of airspace security is not academic. Last March, a number of Russian Tupolev TU-95 “Bear” bombers, also used as long-range maritime patrol planes, entered Irish airspace.
In response, six Royal Air Force Typhoons were scrambled from bases in Scotland and England and headed towards counties Derry and Donegal to intercept, forcing them to alter course.
Quick-reaction aircraft from Nato allies Norway and France also took part in the response.