Dialogue with the Taliban is not the same as appeasement, David Miliband is set to argue in a major foreign policy speech in the United States.
He will call on the Massachusetts Institute of Technology to acknowledge that, while the ideological core of the Taliban remains beyond reconciliation, the majority of fighters can be persuaded to lay down their arms.
This will only occur with a "serious effort to address the grievances of those whom President [Hamid] Karzai describes as his 'disaffected patriots'", he will say.
"Without a genuine effort to understand and ultimately address the wider concerns which fuel the insurgency, it will be hard to convince significant numbers of combatants that their interests will be better served by working with the government than by fighting against it," Mr Miliband will warn.
Britain wants the Afghan government to intensify its steps to confront corruption to build confidence in the country's political systems.
Mr Miliband will also call for all tribal, ethnic or other groups to be given a "stake" in the political settlement being sought at the grand peace jirga (a tribal assembly of elders) set for April 29th.
He also wants to see district and provincial governors empowered and a more even balance between the parliament and president.
"Dialogue is not appeasement and political space is not the same as veto power or domination," the foreign secretary will say.
"The military build-up of international and Afghan capacity concentrates the mind. Dialogue provides an alternative to fight or flight."