Two Americans confirmed dead in Brussels attacks
At least two Americans died in the terrorist attacks on a metro station and at the airport in Brussels, a US official has confirmed.
The official did not identify the two people but confirmed their deaths as US Secretary of State John Kerry arrived in Belgium.
Mr Kerry is holding counter-terrorism talks with European and Belgian officials and attend a memorial.
Thirty-one people died in the attacks and scores more were injured.
So-called Islamic State (IS) militant group has said it was behind the attacks.
After meeting with Belgian Prime Minister Charles Michel, Mr Kerry said "United States is praying and grieving with you for the loved ones of those cruelly taken from us, including Americans, and for the many who were injured in these despicable attacks."
The families of the two people who died in the attacks on Tuesday have been informed, the official said, but did not have any more details.
Two Dutch nationals who had been living in New York City also died in the attacks, Belgian and Dutch authorities have confirmed.
Siblings Alexander and Sascha Pinczowski were on the phone with a relative at the Brussels airport on Tuesday when the phone went dead.
The family has said they are "grateful to have closure on this tragic situation".
Mason Wells, a 19-year-old Mormon missionary from the US state of Utah, was badly injured in the attacks and is recovering in hospital.
Mr Wells narrowly escaped the Boston Marathon bombings in 2012 and was in France during November's Paris attacks.
Two other Mormon missionaries were also injured in the attacks.
The State Department has said about a dozen US citizens were injured in total.
Mr Kerry defended Belgium's counter-terrorism tactics, which have been scorned by critics as un-coordinated.
"People are jumping to conclusions," he said. "I think they are looking for things that sometimes are very difficult to analyse in the immediate aftermath of something".
He called criticism of Belgium's tactics "frantic" and "inappropriate".
All governments must improve on their efforts to stop terrorism, he said, and Brussels has made strides in the past year.
"We will not be deterred," Mr Kerry said, and said the fight against IS will be relentless. "We will come back with greater resolve - with greater strength - and we will not rest until we have eliminated your nihilistic beliefs and cowardice from the face of the Earth."