Washington is releasing some $26 million to Yemen in military aid and boosting funds to armies in five other nations, waiving sanctions imposed for recruiting child soldiers, a US official said Thursday.

President Barack Obama on Tuesday fully waived sanctions and lifted bans on international military, education and training assistance to Yemen, Rwanda and Somalia applied under the Child Soldier Prevention Act, said deputy assistant secretary Michael Kozak.

Central African Republic, the Democratic Republic of Congo and South Sudan were also given partial waivers for specific military purposes, while sanctions were maintained on Myanmar, Sudan and Syria, found guilty of the widespread recruitment of children into their armies.

Waivers did not mean the United States was turning a blind eye to the use of child soldiers or providing an "unlimited flow of security assistance," Kozak said.

"The waiver doesn't mean that they are not guilty of recruiting child soldiers. To the contrary, it means they are, and therefore the sanction in law would apply but for the waiver," Kozak said, adding the idea was a bit like "a doctor treating a patient."

"You don't want to do something that's going to kill the patient. If you have al-Shebab take over in Somalia because we couldn't support the government at all, that's not going to help the child soldier problem or any other human rights problem."

For Yemen "the full waiver will free up $25 million in foreign military financing to build the counter-terrorism abilities of their military" and $1.2 million to continue moves to build a professional army.

But Kozak stressed that amid the current instability in Yemen, where Shiite rebels overran the capital last week, "whether it still makes sense to provide assistance as situations on the ground change" would be evaluated by the US government.

About $100,000 will be released for Central African Republic, wracked by unrest since March 2013, which is "trying to stand up a new professional military force... we want to be in a position to support that."

The DR Congo will get around $350,000 in military training assistance, as well as extra funds to be determined to support the navy and activities against the outlawed Lord's Resistance Army of Joseph Kony. Rwanda will also get around $350,000, after dropping its support for M23 rebels in neighboring Congo.

The United Nations praised Myanmar last week for making progress in thinning the numbers of child soldiers in the ranks of its armed forces.

But Kozak said the US sanctions remained in place because in Burma "they have got internal conflicts going on, which are ones that they should be ending. They're not conflicts for the survival of the country."