A group of about a dozen U.S. State Department officials have taken the unusual step of formally accusing Secretary of State Rex Tillerson of violating a federal law designed to stop foreign militaries from enlisting child soldiers, according to internal government documents reviewed by Reuters.

A confidential State Department "dissent" memo not previously reported said Tillerson breached the Child Soldiers Prevention Act when he decided in June to exclude Iraq, Myanmar, and Afghanistan from a U.S. list of offenders in the use of child soldiers. This was despite the department publicly acknowledging that children were being conscripted in those countries.

Keeping the countries off the annual list makes it easier to provide them with U.S. military assistance. Iraq and Afghanistan are close allies in the fight against militants, while Myanmar is an emerging ally to offset China's influence in Southeast Asia.

Documents reviewed by Reuters also show Tillerson's decision was at odds with a unanimous recommendation by the heads of the State Department's regional bureaus overseeing embassies in the Middle East and Asia, the U.S. envoy on Afghanistan and Pakistan, the department's human rights office and its own in-house lawyers.

"Beyond contravening U.S. law, this decision risks marring the credibility of a broad range of State Department reports and analyses and has weakened one of the U.S. government's primary diplomatic tools to deter governmental armed forces and government-supported armed groups from recruiting and using children in combat and support roles around the world," said the July 28 memo.

Reuters reported in June that Tillerson had disregarded internal recommendations on Iraq, Myanmar and Afghanistan. The new documents reveal the scale of the opposition in the State Department, including the rare use of what is known as the "dissent channel," which allows officials to object to policies without fear of reprisals.

The views expressed by the U.S. officials illustrate ongoing tensions between career diplomats and the former chief of Exxon Mobil Corp appointed by President Donald Trump to pursue an "America First" approach to diplomacy.

The child soldiers law passed in 2008 states that the U.S. government must be satisfied that no children under the age of 18 "are recruited, conscripted or otherwise compelled to serve as child soldiers" for a country to be removed from the list. It currently includes the Democratic Republic of Congo, Nigeria, Somalia, South Sudan, Mali, Sudan, Syria and Yemen.

Foreign militaries on the list are prohibited from receiving aid, training and weapons from Washington unless the White House issues a waiver based on U.S. "national interest." In 2016, under the Obama administration, both Iraq and Myanmar, as well as others such as Nigeria and Somalia, received waivers.

At times, the human rights community chided President Barack Obama for being too willing to issue waivers and exemptions, especially for governments that had security ties with Washington, instead of sanctioning more of those countries.