How European countries deal with the detention of migrant children Some EU countries detain children, but they don't separate migrant families.

LONDON -- In response to mounting criticism of the policy of separating migrant children from their families, President Donald Trump signed an executive order Wednesday that he said is about "keeping families together" and "ensuring we have a powerful, very strong border."

"I think the word 'compassion' comes into it," Trump said. "My wife feels strongly about it. I feel strongly about it. Anybody with a heart would feel this way."

The practice of separating children from their parents and detaining them had sparked widespread criticism from other world leaders, including the United Kingdom’s Prime Minister, Theresa May.

"The pictures of children being held in what appear to be cages are deeply disturbing," Theresa May told lawmakers Wednesday. "This is wrong. This is not something that we agree with. This is not the United Kingdom's approach."

It is unclear how and where migrant children who are detained in the U.S. will be housed following the executive order. But America's policies toward migrant children remain much different than those of European Union member states. While some EU countries do detain child migrants, they are not separated from their parents, and EU law says that asylum-seeking families should be kept united as much as possible.

So how do European countries deal with asylum-seeking families and children? Here’s what you need to know.

How many migrant children are detained in the EU?

Children have represented up to a third of migrant arrivals in the EU since the summer of 2015, according to a 2017 report by the European Union Agency for Fundamental Rights. But there is no comparable and reliable data on how many migrant children are detained in the EU, the agency found.

The agency did analyze data provided by EU member states on the number of children detained on three specific days, however: Dec. 31, 2015, March 31, 2016, and Sept. 1, 2016.

On those days, no children were detained in Cyprus, Denmark, Estonia, Germany, Ireland, Italy, Malta, Spain or the United Kingdom.

Bulgaria had the largest number of children in detention on any one day -- 458, all of whom were in detention with their families on Sept. 1, 2016. On the same day, Greece had 255 children in immigration detention; only seven of them were detained without their families. Those who were detained without their families had arrived alone without parents or guardians, and had not been separated from their families by authorities, the report said.

Hungary, Poland, and Slovakia were other countries that detained a large number of children on some of the days studied in the report.

Overall, while these numbers are not a complete picture of the number of children detained each day, they are significantly smaller than the approximately 2,000 migrant children who had been detained and separated from their families by U.S. authorities over the past six weeks.

Where are detained migrant children held and what are the conditions like?

Most EU countries that allow the detention of children have established specialized spaces for them -- either as part of existing detention centers or separate facilities, according to the report by the European Union Agency for Fundamental Rights.

But many of these facilities still resemble prisons, the report found, and they are often surrounded by barbed wire.

Many officers in these facilities wear military fatigues and use handcuffs to transport detainees, the report found, and in most of the cases the agency examined, staff members had no specific training on child protection.

Human rights organizations have criticized some European countries for detaining children too long and in "degrading" conditions.

For example, in a 2016 report, Human Rights Watch found that Greece had been arbitrarily detaining children for prolonged periods of time, often in "poor and degrading conditions" at police stations, protective custody or in pre-removal detention centers and closed facilities on the Greek islands.

"In some cases, children said they were made to live and sleep in overcrowded, filthy, bug- and vermin-infested cells, sometimes without mattresses, and were deprived of appropriate sanitation, hygiene, and privacy," the report found.

How long do children stay in detention in the EU?

The European Union Agency for Fundamental Rights report found that the time children spent in detention varied from a few hours to several months. Most of the children detained were boys. On the days that the agency examined in its 2017 report, three countries -- Luxembourg, Poland, and Slovakia -- had detained infants with their families. Four countries -- Belgium, Luxembourg, Slovenia, and Sweden -- held children for 15 days or less on the days examined.

On the dates the agency studied, two unaccompanied children had been detained for more than four months: a 15-year-old boy in Latvia had been detained for 195 days and a 16-year-old boy in Poland had been detained for 151 days.

Questions about a child's age, irregular border crossings and waiting for a guardian to be appointed were among the reasons EU countries gave for detaining children for longer periods of time.

What does the UN and the EU say about separating families?

Under international law and binding European directives, detention of unaccompanied children -- children who arrive in a country without their parents or adult guardians -- can only be used as a last resort. Such detention is reserved for exceptional circumstances, and the law mandates that the child's best interest must to be kept in mind.

Article 9 of the U.N. Convention on the Rights of the Child requires countries to make sure that children are not separated from their parents against their will unless competent authorities "subject to judicial review determine, in accordance with applicable law and procedures, that such separation is necessary for the best interests of the child." This separation might be necessary in cases where parents are abusing or neglecting their children, the article says.

EU law also states that countries have to do what they can to ensure that families are not separated. Article 12 of the Reception Conditions Directive states that EU member states "shall take appropriate measures to maintain, as far as possible, family unity" if asylum seekers are provided with housing by the host countries.

Article 11 of the same document states that "minors shall be detained only as a measure of last resort" and after it has been established that there are no better alternatives. The policy also says that the detention of children has to be for the shortest period of time possible and in a place suitable for them. Additionally, detained families need to be held in separate facilities to ensure their privacy.