Mullah Baradar's arrest has coincided with the Nato push in the Marjah area of Helmand province in Afghanistan
Afghanistan's punishing war is entering a new phase and Pakistan has made it clear it can and must play a leading role.
The sudden significant capture of Mullah Abdul Ghani Baradar, second in charge in the Taliban hierarchy, comes at a crucial point.
Talk of negotiation is now taking centre stage, a strategy in parallel to a powerful military assault against Taliban strongholds in southern Afghanistan.
"There has been a change in Pakistan's attitude," said Pakistani author Ahmed Rashid, who has written extensively about the close links between Pakistan's military intelligence, the ISI, and Taliban leaders.
"Pakistan now wants to dominate any kind of dialogue that takes place."
Mullah Baradar, reported to have been picked up by Pakistani and US intelligence agents in the southern Pakistani city of Karachi, may have become too independent.
Sources in Kabul say he and his envoys have been involved in secret talks with the Afghan president in Kabul, his representatives in southern Afghanistan and outside the country.
One senior Afghan official who, like others, is not commenting publicly for now, said: "This may be good for public opinion but, for us, it can have a negative impact.
"It was easier for us to talk to him."
A Western source involved in the process expressed frustration this channel was now being exposed and, for the moment, stopped.
More arrests have now been reported including two Taliban "shadow governors" who reported to Mullah Baradar.
Reports from Kandahar last month speculated that Mullah Baradar would soon be arrested because of growing tensions with Mullah Omar.
The two men have been close confidants. The Taliban leader had appointed him as one of his two main deputies after the movement was ousted from power in 2001.
Mullah Baradar rose to become the key military commander as Mullah Omar found it increasingly difficult to operate in the open.
"Pakistan has accomplished two objectives," remarked Lt Col Tony Shaffer, who served as an intelligence officer in Afghanistan in 2003, and is now at the Center for Advanced Defense Studies in Washington.
"They've shown us in the West they're willing to co-operate and they've taken out someone they didn't control."
Pakistan has always denied senior Taliban leaders are living on its soil, saying they go back and forth across the porous border with Afghanistan.
Unlike the Bush administration, Barack Obama's team has been urging Pakistan, privately and publicly, to take action against the Taliban leadership and their sanctuaries in the tribal areas, as well as in cities like Quetta and Karachi.
Mullah Omar was reported to be at loggerheads with Mullah Baradar
Since 2001 the Pakistan military has moved against al-Qaeda and more recently, Pakistani Taliban leaders. But it's long made it clear it won't move against the Afghan Taliban and other powerful Afghan commanders linked to the insurgency.
Islamabad has regarded its long-standing Taliban connections as a key asset in neighbouring Afghanistan.
Now that the Afghan government and its Nato allies have made reintegration of low-level Taliban fighters - and reconciliation with more senior commanders - a key priority, Pakistan wants to play a role in bringing the Taliban to the negotiating table.
Pakistan's army chief, Gen Ashfaq Kayani, has been indicating their readiness.
Sphere of influence
In a rare press briefing in February, he made it clear "we have opened all doors" to co-operation with Nato and Afghan forces in Afghanistan.
But he also asserted "our strategic paradigm has to be realised". For Pakistan, this means a friendly Afghanistan that is part of its sphere of influence - and where India, still regarded as a threat, plays no major role.
Washington seems to accept Pakistan can be a broker.
US Special Representative for Afghanistan and Pakistan Richard Holbrooke, on a visit to Kabul, told BBC's Persian TV: "Pakistan's ISI can play a role in negotiations and I support that role.
"Pakistan has an influence in this area and has a legitimate security interest."
The former ISI head, retired Gen Hamid Gul, talked about this relationship with his trademark bluntness. Speaking to me in an interview on the BBC's Newshour programme, he said: "America is history, Karzai is history, the Taliban are the future."
Pakistan, he warned, "would be unwise to cut all contacts and goodwill with the future leaders of Afghanistan".
A growing role for Islamabad causes unease in Kabul. President Karzai and key members of his team have repeatedly criticised the role of the ISI in providing sanctuary to Taliban leaders.
The president has made it clear he wants any reconciliation to be an Afghan-led and controlled process.
The US is hailing its relationship with Pakistan
There's been no official announcement from Kabul yet to Mullah Baradar's capture.
A few years ago, Kabul opened contacts with another senior Taliban leader, Mullah Mansoor Dadullah, who had also fallen out with Mullah Omar, only to have Pakistan capture him in early 2008. At the time, a senior Afghan intelligence official expressed anger and dismay.
Dutch journalist Bette Dam, author of a recent book on Hamid Karzai, has written of years of contacts between the president and Mullah Baradar, who are both from the Popalzai tribe.
Mullah Baradar is said to have come to the rescue of Hamid Karzai when he was threatened by Taliban fighters in the southern province of Uruzgan after the 9/11 attacks.
On her most recent visit to Uruzgan in December, Ms Dam said that she had been informed that Mullah Baradar made a visit to Kabul last year.
Afghans in the province - the birthplace of Mullah Baradar - also spoke of "how powerful and increasingly independent he had become in the Taliban movement, establishing his own committees and charities, and operating though his own tribal networks".
The question now is what impact will his arrest have on any future negotiations with the Taliban and on Pakistan's role in this process.
Islamabad is being hailed in Washington for its co-operation with the US.
For the Americans, this success comes only weeks after the CIA suffered its biggest blow in decades. It lost seven operatives when a double agent detonated a suicide vest at their base in the eastern province of Khost.
But many key details of this latest operation are still unclear. Reports are now emerging that Mullah Baradar may have been detained earlier than the dates cited in the original story in the New York Times.
It's also still not clear how much involvement US intelligence had in the raid and how much access they have to this valuable source, who has an enormous store of knowledge about the movement, including their contacts with the ISI.
One Western source in Kabul said that the Americans were exaggerating the level of co-operation.
US intelligence officer Col Shaffer argues that what happens next is of key importance.
"We should watch very closely what happens," he remarked.