The United States has offered to help Pakistan investigate a deadly five-hour siege on Karachi's international airport.
The offer came after Pakistani Taliban fighters disguised as police guards stormed the facility - the country's busiest - setting off explosions in an attack that left at least 29 people dead.
"The United States condemns the attack on the Karachi airport. And our hearts go out... to the families of the victims and those who were wounded in that attack," White House spokesman Josh Earnest said on Monday
Washington has offered "assistance to the relevant Pakistani authorities investigating this crime," added State Department deputy spokeswoman Marie Harf, although she was not aware if the offer had been taken up.
Operations at the Jinnah international airport resumed on Monday afternoon, hours after the end of overnight fighting that also left at least two dozen people wounded.
A spokesman for Tehreek-e-Taliban Pakistan said the attack was in retaliation for the treatment of Taliban prisoners, air raids in North Waziristan and for the drone strike death last year of Hakimullah Mehsud, a top Taliban commander.
In a Twitter statement, the group said: "We have yet to take revenge for the deaths of hundreds of innocent tribal women and children in Pakistani air raids. It's just the beginning, we have taken revenge for one, we have to take revenge for hundreds."
Al Jazeera's Kamal Hyder, reporting from Islamabad, said the statement came from group's Shahidullah Shahed.
The raid involved heavily armed attackers disguised as security personnel, who hurled hand grenades and fired automatic weapons as they targeted the airport's cargo terminal.
The army initially said it had regained control of the airport at dawn after the siege, but relaunched their operation after explosions and shooting were heard in the morning.
The dead included at least 10 of the attackers, officials said.
Al Jazeera's Hyder said the attackers were wearing uniforms of the airport security force and and used fake IDs to enter the terminal.
Most passengers were moved to a secure location overnight and all local and international flights were suspended, officials said.
However, witnesses told Al Jazeera that more than 60 people were stranded in the main terminal for several hours as they waited for security clearances.
Television pictures showed a large fire raging at the airport as ambulances ferried casualties away.
Our correspondent said: "This is not the first time. There have been two major attacks in the past, one in Karachi and another in Kamra airbase [in Attock district in Punjab]. There was another attack on Peshawar airport which was foiled.
Security was increased at airports and military installations across Pakistan following the Karachi assault.
Source: Al Jazeera and agencies