The pledge comes in a new policy document on the issue published by the UK government on Wednesday.
Its publication is particularly timely, with fresh concern about global security following the controversial US decision this week to withdraw from the Iran nuclear deal, a move roundly condemned by EU leaders.
There are also lingering concerns in Europe about US President Donald Trump’s long-term commitment to Nato which he has previously branded as “obsolete.”
Trump has accused several Nato members, including Germany, of failing to pull their weight financially in the western alliance.
The UK internal document, published on Wednesday and seen by this website, also calls for a “dynamic” security treaty that can tackle “new threats and changes in technology.”
It states, “As the UK leaves the EU we are unconditionally committed to European security and want to work closely with our European partners to keep all of our citizens safe.
“We wish to develop a new partnership with the EU which builds on the breadth and depth of our shared interests and values, and goes beyond any existing third country arrangements.”
The document focuses on how the UK will look to achieve this vision.
It covers both internal and external security, and will form the basis of ongoing negotiations with the EU.
The security partnership between the two sides should be a “core chapter” of the UK-EU future framework, which will be concluded alongside the withdrawal agreement later this year, it says.
Britain is keen to ensure that there is “no drop off in our mutual effort in support of European security.
“To best enable the UK and EU act together, our partnership should be anchored by a combination of political and legal agreements,” the 40-page policy paper concludes.
It says, “Europe’s security is the UK’s security and the UK is unconditionally committed to maintaining it.”
Meanwhile, a proposed 22-fold increase in the EU defence budget could mean less money being spent on key areas, UK ECR group MEP Geoffrey Van Orden has warned.
In its draft budget for the period 2021-2027, the European Commission allocates €27.5bn for defence and security. However, Van Orden, his group’s defence spokesperson, fears this steep rise is not good news for the security of Europe.
He said, “The Commission has always seen EU defence as an aspect of European integration and not in terms of increased military capability. Certain member states will calculate their EU contribution as part of their national defence expenditure and then have the excuse to spend less on what really needs to happen, namely improving their national armed forces.
“Second, the deliberate development of a separate EU defence organisation is a distraction for those 22 EU countries that are also Nato members. Far from strengthening the Atlantic alliance, separate EU structures will create division, not just between an EU caucus and the United States but between European countries within the EU and those outside, including two of the most powerful European military powers - Turkey, and in due course, Britain.
“Third, France will see this as a further opportunity to enhance its defence research, production and exports and will aim to exclude the UK as far as possible - in spite of its bilateral defence treaty with us,” said the ECR group deputy.
“For all these reasons, Britain needs to do all that it can to maintain a degree of influence in EU defence structures while reinforcing its position as, overwhelmingly, the leading European Nato and a global military power.”
Van Orden, a former senior British military officer, added, “The fact is the European Commission is, at heart, a rigid ideological structure driven by one idea - European political integration. The EU’s defence ambitions are a key part of this. No wonder the Brexit negotiations have proven so difficult.”