David Cameron will stick to a commitment to increase defence spending above the rate of inflation after 2015, it has emerged.
The prime minister made the pledge in 2010, at a time when the coalition thought the structural deficit would be cut in this Parliament.
Government sources said he would not "resile" from it - despite plans for further spending cuts beyond 2015.
Mr Cameron is currently on a trip to North Africa.
The renewed commitment comes as Defence Secretary Philip Hammond prepares to publicise the Ministry of Defence's £160bn equipment plan for the next 10 years for the first time.
The list includes nearly £36bn for a new generation of nuclear-powered submarines, almost £19bn for combat aircraft, and around £17bn for Royal Navy warships.
Mr Hammond will say he has finally eliminated a "black hole" in the defence budget that the coalition government says it inherited from the former Labour government.
Last week, Chancellor George Osborne said government spending cuts must continue until 2017 - the latest GDP figures showed the UK economy shrank by 0.3% in the last three months of 2012, fuelling fears the economy could re-enter recession.
Many Conservative backbenchers have been pushing for the MoD to be exempt from the next round of reductions - and Mr Hammond himself is said to be resisting any further cuts - especially after the recent hostage crisis in Algeria and the Western intervention in Mali.
BBC political correspondent Iain Watson said: "There are particular tensions over departmental budgets for the financial year 2015/16 which haven't yet been finalised, but which will come into effect just before the next general election."
He said other government departments were now likely to be concerned that the "spending axe" will cut more deeply into their budgets.
But, our correspondent added: "Defence spending will still be 8% lower by 2015 than it was when the government came to power."
On a visit to Algeria on Wednesday, David Cameron said that the international community should use "everything at its disposal" to fight terrorism.
He also announced that the two countries had agreed a security partnership, including co-operation on border and aviation security, as well as joint action on trade, investment and education.
The UK has also invited Algeria to participate in a joint contingency planning exercise to share experience in responding to crisis situations, in the wake of the gas plant hostage crisis in which up to six Britons died.
The UK announced on Tuesday it is to send 330 military personnel to Algeria's neighbour Mali and west Africa to support French forces battling Islamist militants.
The deployment will include as many as 40 military advisers in Mali and 200 British soldiers in neighbouring African countries, to help train the Malian army.