Seven Afghans were killed and 15 wounded in the coordinated daylight attack, which sent foreigners dashing for cover and terrified the city from midday well into the night as U.S. helicopters buzzed overhead. No embassy or NATO staff members were hurt.
Late Tuesday, at least two gunmen remained holed up on the top floors of an apartment building from which they and other militants had attacked the heavily fortified embassy.
The militants' seeming ability to strike at will in the most heavily defended part of Kabul suggested that they may have had help from rogue elements in the Afghan security forces. The attacks also coincided with suicide bombings elsewhere in the capital – the first time insurgents have organized such a complex assault against multiple targets in separate parts of the city.
The Taliban claimed responsibility for the attack, though Kabul's deputy police chief said he thought an affiliated organization, the Haqqani network, carried it out.
The Taliban and related groups have staged more than a dozen assaults in Kabul this year, including three major attacks since June. That represents an increase from years past and is clearly intended to offset U.S. claims of weakening the insurgents on southern battlefields and through hundreds of night raids by special forces targeting their commanders.
The Obama administration declared that it wouldn't allow Tuesday's attack to deter the American mission in Afghanistan, warning the attackers that they would be relentlessly pursued.
Even so, the U.S. Embassy in Kabul canceled all trips in and out of Afghanistan for its diplomats, and suspended all travel within Afghanistan.
High blast walls ring the embassy compound, and there was little damage to the reinforced concrete buildings, many of which are surrounded by sandbags.
Four Afghans were wounded when a rocket-propelled grenade hit the original U.S. Embassy building next to the new embassy, CIA Director David Petraeus told lawmakers on Capitol Hill. Among them was a young girl who was with a group waiting for visas outside the embassy, he said.
Afghan officials said the violence around Kabul resulted in the deaths of three police officers and four civilians. Four of the wounded were caught up in attempted suicide bombings. Six insurgents were also killed, police said.
According to Afghan officials, the attack began just after noon when a car packed with insurgents was stopped at a checkpoint at Abdul Haq square, which is about 300 yards (meters) from the U.S. Embassy. There were a series of large explosions and the insurgents entered a nine-floor building that was under construction overlooking the embassy and the nearby NATO headquarters complex.
Four to five insurgents opened fire on the complex. There was a simultaneous barrage of explosions around the Wazir Akbar Khan area, near the U.S. Embassy and home to a number of other foreign missions. Explosions shook the neighborhood.
Three other insurgents attempted to carry out suicide attacks and all were killed. One was shot on the road leading from the capital to the airport, and the two others when they tried to attack Afghan police buildings in western Kabul, across the city from the embassy.
The bullets detonated one of the militants' explosives vest, wounding two police officers. Another militant detonated his vest at a nearby building, wounding two civilians.
Afghan security forces raided the nine-story building and killed two insurgents, but at least two others remained on the top floors late into the night. U.S. Army helicopters flew over the building and an Afghan army MI-35 attack helicopter opened fire on it with its gatling gun.
It was unclear how much weaponry the insurgents had, but one eyewitness said they were equipped with heavy machine guns, rocket-propelled grenades and possibly a mortar.
Western security officials, speaking on condition of anonymity for security reasons, speculated that the insurgents may have had help smuggling so many weapons into Kabul and the area near the embassy. There have been numerous instances of insurgents infiltrating the Afghan army and police to carry out attacks.
Afghan police Gen. Daoud Amin, deputy police chief of Kabul, said the Haqqani insurgent network was likely behind the attack. The Haqqani network is a Pakistan-based group affiliated with both the Taliban and al-Qaida. It has emerged as one of the biggest threats to stability in Afghanistan.
"This is the first time that we had four suicide bombers in four different places. This is new as previously we had one or maximum two attacks," said Haroun Mir, director of the Afghanistan Center for Research and Policy Studies, a Kabul-based think tank. "The Haqqani network has the full support of al-Qaida and has the capacity to execute sophisticated attacks. It's the only group with this capacity."
The U.S. Defense Department blamed the Haqqani network for a truck bomb that blew up outside an American base over the weekend, wounding 77 U.S. soldiers and killing five Afghans. The attack occurred in eastern Wardak province, an hour's drive from Kabul.
The violence carries an unsettling message to Western leaders and their Afghan allies about the resilience and reach of the Taliban and related organizations. It is also an indication the militants may not be interested in pursuing peace talks with President Hamid Karzai's government or the United States.
White House press secretary Jay Carney said the U.S. would continue to move toward removing soldiers sent in as part of the 2009 troop surge and would keep training local forces.
"This will in no way deter our commitment to the mission, which is to provide for security in the country as we work to transition a security lead to the Afghan national security forces," Carney said.
NATO Secretary-General Anders Fogh Rasmussen echoed this, saying in Brussels that the "enemies of Afghanistan" were trying to disrupt the handing over of security responsibility to the Afghans.
Karzai said the attacks would not deter Afghan security forces from taking full responsibility for security by the time the international community withdraws all its combat troops.
"By carrying out such attacks terrorists cannot stop the transition of security from international to Afghan forces," Karzai said in a statement.
The U.S. and other foreign troops intend to withdraw from the country by the end of 2014. President Barack Obama has ordered the withdrawal of 33,000 troops by the end of next summer, and some of America's international partners are making plans to remove some of their forces. There are now about 131,000 foreign troops in Afghanistan, with 90,000 from the United States.
The expansion of the Afghan army and police is critical to NATO's exit strategy. Earlier this summer, the alliance handed over responsibility for security in seven areas, including two provinces. But violence has increased in some of those places.
The U.S. hopes to have 325,000 Afghan army and police in the field by the end of 2014. But the Afghan forces have been plagued by desertions. And on Tuesday, the Pentagon announced it will try to cut the multibillion dollar cost of training the forces.
(Associated Press writers Heidi Vogt and Rahim Faiez in Kabul, and Bradley Klapper and Kimberly Dozier in Washington, contributed to this report.)