The computer hardware used to coordinate the operational functions of US nuclear forces still relies on floppy disks, a new report has revealed.

The US Government Accountability Office (GAO) has published their report highlighting how outdated some of the country's key computer hardware and software has become.

The defence department's system that coordinates operational functions of intercontinental ballistic missiles, nuclear bombers and tanker support aircrafts is reported to be 53 years old.

The system, which still uses 8-inch floppy disks, runs on an IBM Series/1 computer from the 1970s.

However, some of the treasury department's core systems are said to be even older - having been in place for 56 years.

The 'master files' for both personal and business tax data are said to be written in assembly language code, described as "a low-level computer code that is difficult to write and maintain".

Although the defence department is planning to have their system upgraded by the end of the 2017 fiscal year, there are only general plans - with no timeframe - for an upgrade of the treasury systems.

The GAO highlights a number of issues with many of the older 'legacy systems' - such as a reliance on outdated programming languages, parts becoming obsolete and a lack of support.

The organisation says: "Legacy systems may become increasingly more expensive as agencies have to deal with the [...] issues and may pay a premium to hire staff or contractors with the knowledge to maintain outdated systems. For example, one agency [...] reported re-hiring retired employees to maintain its COBOL systems" (COBOL is a programming language developed in the 1950s and 60s).

GAO adds that government agencies spent about $61 billion (around €5.45bn) operating and maintaining systems in 2015 - over three quarters of the federal IT budget.