The strikes, including a suicide motorbike bombing in the relatively calm Afghan capital, came just as Vice President Joe Biden was leaving the country after a visit during which he praised advances against the militants while acknowledging they are "fragile and reversible."
Apart from the Taliban's traditional heartland in the south, the insurgents have been particularly active in the east near the border with Pakistan. Both Afghanistan and the United States have often called on Islamabad to do more to eliminate militant safe havens on its side of the frontier, and Biden flew to Pakistan Wednesday morning for meetings with officials there, saying a sustained partnership with the U.S. was vital in defeating al Qaeda and Taliban extremists.
The U.S. administration has been claiming successes in the nearly decade-long war against the Taliban, particularly after NATO bolstered its forces with the addition in mid-2010 of more than 30,000 troops most Americans. The boost was aimed at pressing the insurgency, especially in the south. With a total of about 140,000 international troops now in Afghanistan, the coalition hopes to make enough advances against the militants for Afghans to be able to take over the responsibility for securing their nation by the end of 2014.
But while they have been squeezed in the south, the Taliban have put on several displays of power in recent weeks, including suicide attacks, roadside bombs and shootings across the country.
Roadside bombs have been the deadliest weapon in the insurgent arsenal against international forces in the course of the Afghan war. Two such attacks on Wednesday killed four international troops three in one blast in the east and one more in the south. A fifth international service member was killed in an insurgent attack in eastern Afghanistan, and another died in the east from a "non-battle related injury," NATO said. It did not provide the nationalities of those killed or more specific locations for the attacks.
The deaths brought the number of international forces to have died so far this year in Afghanistan to 17, including at least eight Americans.
Last year was the deadliest of the war for international forces, with more than 700 killed, compared to just over 500 in 2009.
Wednesday's violence began in crowded western Kabul during the morning rush hour, when a suicide bomber on a motorbike targeted a minibus carrying Afghan intelligence service employees. The attack left at least two people dead and wounded more than 30.
The powerful blast shattered the windows of dozens of houses. The suicide bomber's body lay in the street near the wreckage of his motorbike as police and intelligence officials cordoned off the area.
President Hamid Karzai's office initially said four people had been killed in what he described as an attack "against all Islamic and human principles." The presidency later revised the number to two, saying the new figure was based on more complete information several hours after the bombing.
The Interior Ministry said one of the dead was an intelligence service member and the other a civilian, while 32 people were wounded, including six members of the intelligence service.
About an hour later in the troubled eastern province of Kunar, a remote-controlled roadside bomb killed a colonel with the intelligence service and his driver, and wounded two bodyguards, said Abdul Saboor Allahyar, deputy chief of Kunar's provincial police.
The Taliban claimed responsibility for both attacks.
The insurgents have proved resilient despite repeated offensives by the U.S.-led military coalition. An extra contingent of 1,400 U.S. Marines are to be deployed in the coming months in the southern province of Helmand, which along with neighboring Kandahar have seen some of the fiercest fighting.