David Cameron talks tough on the global stage at G8

His performance saw G8 leaders rally behind his call as he also made diplomatic advances on the Falklands, the BP oil spill crisis, budget cuts and the economy.

In a clear signal that Britain will not be pushed around under his leadership, the Prime Minister delivered a statesmanlike “hands off the Falklands” message to Argentine president Cristina Kirchner.

In talks with US President Barack Obama, Mr Cameron then went on to stress BP’s vital importance to the British economy. He saw off a further challenge from the American president over Britain’s right to dictate its own timetable for clearing Labour’s debt legacy.

In a surprise breakthrough, world leaders at the G8 Summit in Muskoka, Canada, set Afghan President Hamid Karzai an ultimatum for his forces to take responsibility for his country’s security.

It was the first time the international community had spelt out a timescale to withdraw troops and came 24 hours after the PM paved the way for a 2015 deadline to pull out Britain’s 10,000-strong force.

A closing statement pledged to make “concrete progress” to reinforce the country’s justice system and expand the capacity of the Afghan national security forces to “assume increasing responsibility for security within five years”. The breakthrough came as Britain paid tribute to war heroes in Afghanistan on Armed Forces Day and Britain’s death toll rose to 308.

The international boost to Mr Cameron’s hopes of bringing the troops home within a Parliament rounded off an assured performance by the Prime Minister.

In a passionate rallying cry, he told the summit that six months into an 18-month military surge, the West was winning the battle against Al Qaeda and the Taliban.

He insisted the allies had a “clear plan” to build Afghan forces “to a level where they can provide their own security and prevent Al Qaeda returning.”

Mr Cameron also made clear his “complete confidence” in General David Petraeus, the new US military commander in Afghanistan but he urged other nations to play their part in restoring security and to “match the military surge with new energy for a political solution”.

In a signal of Mr Cameron’s growing stature, he was asked to lead the G8 discussion on Afghanistan by the summit’s chairman, Canadian PM Stephen Harper.

Mr Cameron held talks with Mr Obama on strategy in Afghanistan. He also took the opportunity to discuss the oil spill crisis, reiterating his warning that harsh penalties against BP could lead to the “destruction of the company” and have a damaging impact on the British and US economies.

Mr Cameron was also boosted by support for his decision to press ahead with slashing public spending to reduce Britain’s deficit. The final summit agreement gave the go-ahead to industrialised nations, including the UK, to begin deficit reductions while allowing the US to continue “fiscal stimulus” spending to boost demand.

Mr Cameron and Mr Obama seemed keen to smooth over transatlantic differences on the economy, insisting Britain and the US were “aiming in the same direction”.

Mr Obama praised the PM for being “prepared to make difficult decisions” and said the special relationship between Britain and the US was “built on a rock-solid foundation and is only going to get stronger”.

Amid broad agreement on key issues, Mr Cameron faced a showdown with Argentina’s President Kirchner over her desire to seize the Falklands from Britain.

The pair were expected to meet over a dinner at the opening of the G20 summit in Toronto and he was said to be ready to read her the riot act over her “Malvinas” claims.

However, there is no such tension between Mr Cameron and German Chancellor Angela Merkel, who will watch England v Germany in the World Cup together.

The Prime Minister admitted he was “excited but just a little bit anxious” about the outcome of the match.