On this state of the NATO Alliance, which was founded in 1949, the Prime Minister is expected to say:
Seventy years on, we are rock solid in our commitment to NATO and to the giant shield of solidarity that now protects 29 countries and nearly a billion people.
The fact that we live in peace today demonstrates the power of the simple proposition at the heart of this alliance: that for as long as we stand together, no-one could hope to defeat us - and therefore no-one will start a war.
This essential principle is enshrined in Article 5 of the North Atlantic Treaty: that if any one of us is attacked, all of us will go to their defence.
If NATO has a motto, it is: One for all, and all for one.
This doctrine of coming to one another's aid, incarnated by NATO, provides the single most important explanation for why the British people and hundreds of millions of our friends live in peace and freedom today. Everything our peoples hold dear - from liberty and democracy to their jobs, homes, schools and hospitals - would not be secure and could not flourish without the peace that NATO is designed to guarantee.
But history shows that peace cannot be taken for granted and even as we celebrate this anniversary, we must ensure that our deeds match our words.
On the UK's contribution to Euro-Atlantic security the Prime Minister is expected to say:
For the UK's part, we spend over 2% of GDP on defence.
We are making the biggest contribution of any European ally to NATO's Readiness Initiative by offering an armoured brigade, two fighter squadrons and six warships, including the Royal Navy's new aircraft carriers.
As allies and friends, we must never shy away from discussing new realities, particularly NATO's response to emerging threats like hybrid warfare and disruptive technologies including space and cyber.
