President Donald Trump's decision to cancel Afghan peace talks will cost more American lives, the Taliban said on Sunday while the US promised to keep up military pressure on the militants, in a stunning reversal of efforts to forge a deal ending nearly 20 years of war in Afghanistan.

The Islamist group issued a statement after Trump unexpectedly canceled secret talks planned for Sunday with the Taliban's major leaders at the presidential compound in Camp David, Maryland.

He broke off the talks on Saturday after the Taliban claimed responsibility for an attack in Kabul last week that killed an American soldier and 11 others.

Zabihullah Mujahid, a Taliban spokesman, criticized Trump for calling off the dialogue and said US forces have been pounding Afghanistan with attacks at the same time.

'This will lead to more losses to the US,' he said. 'Its credibility will be affected, its anti-peace stance will be exposed to the world, losses to lives and assets will increase.'

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President Donald Trump's decision to cancel Afghan peace talks will cost more American lives, the Taliban said on Sunday

Trump revealed he called off a secret Sunday meeting with the Afghan President Ashraf Ghani (pictured left and right) and a separate one with the Taliban leaders

President said has 'called off peace negotiations' after they admitted to the Kabul attack in order to build false leverage

In Washington, Secretary of State Mike Pompeo said that Afghan peace talks were on hold and Washington would not reduce US military support for Afghan troops until it was convinced the Taliban could follow through on significant commitments.

The US has recalled a special envoy for Afghanistan Zalmay Khalilzad to chart the path forward, Pompeo said in appearances on Sunday.

When asked on 'Fox News Sunday' whether Afghan talks were dead, Pompeo said: 'For the time being they are.'

'I have been fully supportive of this effort,' Pompeo, a veteran Army officer, said. 'The direction that we have taken at the State Department, the effort President Trump has given us guidance to go deliver on is something that I think is important, it's valuable, I think the timing is just right. We made enormous progress.'

Trump has long wanted to end US involvement in Afghanistan - since his days as a candidate - and American diplomats have been talking with Taliban representatives for months about a plan to withdraw thousands of US troops in exchange for security guarantees by the Taliban.

US and Taliban negotiators struck a draft peace deal last week that could have led to a drawdown of troops from America's longest war.

There are currently 14,000 US forces as well as thousands of other NATO troops in the country, 18 years after its invasion by a US-led coalition following the September 11, 2001, al Qaeda attacks on the US.

Fighting in Afghanistan has continued amid the talks and recent assaults by the Taliban cast doubts over the draft deal.

As violence has escalated, Afghan leaders including President Ashraf Ghani have been increasingly critical of the deal and encouraged the Taliban to enter direct talks.

Secretary of State Mike Pompeo said Sunday that the 'timing is just right' to hold talks with the Taliban after Donald Trump received backlash for scheduling talks on U.S. soil just days before the anniversary of the September 11, 2001 terrorist attacks

When asked whether the collapse of talks put a US troop pullout on hold as well, Pompeo said the issue would be discussed. 'The president hasn't yet made a decision on that,' he said

When asked whether the collapse of talks put a US troop pullout on hold as well, Pompeo said the issue would be discussed.

'The president hasn't yet made a decision on that,' he said on ABC's 'This Week.'

Trump decided to get personally involved to get the agreement to the finish line at Camp David after 'real progress' had been made in talks, Pompeo said.

'President Trump ultimately made the decision,' Pompeo told Fox. 'He said, "I want to talk to (President) Ashraf Ghani. I want to talk to these Taliban negotiators. I want to look them in the eye. I want to see if we can get to the final outcome we needed".'

Trump has touted his skills as a negotiator and personal rapport with world leaders including Kim Jong Un of North Korea, but such one-on-one diplomacy has not led to any breakthrough deals so far.

The president was criticized, even by some fellow Republicans, for having offered to host on US soil a militant group that has killed American troops and had sheltered al Qaeda leader Osama bin Laden after the 9/11 attacks.

'Camp David is where America's leaders met to plan our response after al Qaeda, supported by the Taliban, killed 3000 Americans on 9/11,' US Representative Liz Cheney, a Republican whose father, Dick Cheney, was US vice president at the time of the attacks, wrote on Twitter on Sunday.

Trump said he cancelled peace talks with Taliban leaders after the insurgent group said it was behind an attack in Kabul that killed Sgt 1st Class Elis A. Barreto Ortiz (pictured), 34,

'No member of the Taliban should set foot there. Ever.'

Americans will on Wednesday mark the 18th anniversary of the al Qaeda attacks in New York, Washington and Pennsylvania.

Taliban fighters, who now control more territory than at any time since 2001, launched assaults over the past week that included a suicide attack in Kabul on Thursday that killed US Army Sergeant Elis Barreto Ortiz, 34, from Puerto Rico.

Earlier this month, senior security officials in Kabul said joint air raids by US and Afghan forces against the Taliban have not subsided.

Pompeo said more than 1,000 Taliban fighters have been killed in Afghanistan in the last 10 days.

Nine former US ambassadors warned on Tuesday that Afghanistan could collapse in a 'total civil war' if Trump withdraws all US forces before the Kabul government and the Taliban conclude a peace settlement.

Pompeo downplayed chances of a premature withdrawal.

'President Trump made clear we´re not just going to withdraw because there´s a timeline. We´re only going to reduce our forces when certain conditions are met,' he said on CNN's 'State of the Union.'

He said during an interview with CNN Sunday that the meeting was planned after Taliban leaders had 'committed to us that they would sign an agreement that… said that they would break from Al-Qaeda'.

Pompeo said the US had the agreement 'in hand'.

On Friday, the US envoy negotiating with the Taliban, Zalmay Khalilzad, abruptly returned to Qatar for unexpected talks with the insurgents on the deal that he had described as complete just days ago and it was announced President Ghani had cancelled his American trip.

Trump explained a day later why he will no longer meet with Ghani in wooded hills of Catoctin Mountain Park near Thurmont, Maryland.

'Unbeknownst to almost everyone, the major Taliban leaders and, separately, the President of Afghanistan, were going to secretly meet with me at Camp David on Sunday. They were coming to the United States tonight,' Trump posted to Twitter.

'Unfortunately, in order to build false leverage, they admitted to an attack in Kabul that killed one of our great great soldiers, and 11 other people,' he continued.

'I immediately cancelled the meeting and called off peace negotiations. What kind of people would kill so many in order to seemingly strengthen their bargaining position? They didn't, they only made it worse!'

'If they cannot agree to a ceasefire during these very important peace talks, and would even kill 12 innocent people, then they probably don't have the power to negotiate a meaningful agreement anyway. How many more decades are they willing to fight?' the president concluded in his thread of tweets.

Barreto was the fourth American soldier killed in the past two weeks in Afghanistan.

Pompeo said that he visited with his family Sunday morning at Dover Air Force Base.

'I met his lovely wife and two boys, 11 and four. It's precisely those moments that make you recognize so clearly we have an obligation to reduce risk,' he said of why moving forward with talks with the Taliban and Afghanistan government is important.

Negotiators had been meeting in Qatar and were said to be close to reaching an agreement

Walsh said Trump is 'unfit and a danger to this country' for inviting the Taliban to Camp David

Congressman Eric Swalwell was unimpressed by the timing of the meeting ahead of the 9/11 anniversary

Senator Lindsay Graham applauded Trump on Saturday for canceling the sit-down.

'Great decision by President Trump to cancel the meeting' he told Axios. 'We should hit them back hard militarily.'

But many of Trump's critics were appalled that he would invite the group to the US, ahead of the 9/11 anniversary.

Former congressman Joe Walsh, who plans to run against Trump in the Republican primaries, said the decision made him 'unfit and a danger to this country.'

The killing of two NATO soldiers was the second major attack this week as the Afghan government warned that a US-Taliban deal on ending America's longest war was moving at a dangerous speed.

The NATO Resolute Support mission, whose offices were near the blast, said the two service members were 'killed in action' but initially declined to provide further details or release their names.

Ghani, whose government had been shut out of the US-Taliban talks, had previously said in said in a statement: 'Peace with a group that is still killing innocent people is meaningless.'

A Taliban suicide blast in the center of Kabul on Thursday killed a US soldier, a Romanian service member and at least 10 civilians near the American embassy

Camp David is the historic presidential retreat in the surrounding community of Thurmont, Maryland

Besides the 12 killed in the recent attack, 42 others were wounded, according to Interior Ministry spokesman Nasrat Rahimi.

Surveillance footage showed the bomber's vehicle turning into a checkpoint and exploding and a passer-by trying to sprint away just seconds before the blast.

The Taliban said they targeted vehicles of 'foreigners' trying to enter the heavily guarded Shashdarak area where Afghan national security authorities have offices.

British soldiers at the scene retrieved what appeared to be the remains of a NATO vehicle. Stunned civilians made up most of the victims once again.

The Taliban has said its attacks are meant to strengthen its position in talks with the US and that civilians should stay away from potential targets linked to the Afghan government or foreign 'invaders'.

The recent explosion followed a Taliban attack against a foreign compound late Monday that killed at least 16 people and wounded more than 100, almost all of them local civilians.

The violence continued hours later when the Taliban claimed responsibility for a car bombing outside an Afghan military base in the Logar provincial capital, Puli Alam, with local officials saying four civilians were killed and 11 others wounded.

Then the Afghanistan Independent Human Rights Commission confirmed that its acting leader in Ghor province, Abdul Samad Amiri, had been kidnapped by the Taliban while traveling and shot dead late on Wednesday.

Afghan security personnel arrive at the site of car bomb explosion in Kabul on Thursday in the second major attack in a week

An injured man is carried into a hospital after the car bomb explosion that left 42 people wounded

Doctors rush to help a man who was injured in the suicide car bombing on Thursday in Kabul

On Friday, Khalilzad met with Taliban lead negotiator Mullah Abdul Ghani Baradar and the commander of US forces in Afghanistan, Gen Scott Miller, with Qatar's foreign minister present, Taliban spokesman Suhail Shaheen said in a tweet late in the evening.

Both Thursday's and Friday's meetings were 'positive,' he said.

The Afghan government has raised serious concerns about the deal, including in new comments on Thursday as the latest Kabul bombing occurred.

'Afghans have been bitten by this snake before,' Omer said, recalling past agreements from which the Afghan government has been sidelined.

'Where there is no feeling of ownership there is no safety,' he said.

The Taliban, at their strongest since their 2001 defeat by a US-led invasion, have refused to negotiate with the government, calling it a US puppet.

And yet the US hopes its deal with the Taliban will bring the militant group to the table for intra-Afghan talks to begin ahead of Afghanistan's presidential election on September 28.

The Afghan government has said it shares the concerns raised this week by several former US ambassadors to Afghanistan.