Children across Japan are returning to school this week for the new semester, but elsewhere in the world as many as 263 million children won’t be so lucky. Of these out-of-school children, 27 million live in conflict zones.

Japan is already doing a lot to help these children receive an education. Japan is the fifth-largest donor country to education in the world, contributing $691 million in official development assistance in 2015, the latest year for which full data is available. Since 2000, Japan has constructed more than 5,500 primary and secondary schools in 46 countries. But many of these schools are at risk when armed forces and armed groups target them for attack or military occupation.

Among the thousands of schools constructed with Japanese funds are more than 800 in Afghanistan alone. But schools aren’t always used for teaching children in Afghanistan. In some cases, the armed forces or armed groups convert the schools into military bases or barracks.

Take, for example, the middle school in Postak Bazaar village, Baghlan province. In 2010, members of the Afghan National Police, a government paramilitary counter-insurgency force, set up their military base inside the school. Then the Taliban attacked. Following that attack, the bloodstains on the school walls wouldn’t wash away. “We had to chip it away from the wall with an ax,” a school official told Human Rights Watch.

After the Taliban retook the area, their fighters also slept in the school. By 2015, government forces were back, and established their base with sandbagged positions on the second floor, while students tried to continue their schooling below.

Alarmed school officials obtained a letter from the Kabul authorities ordering the forces to leave, but their commander ignored it. At exam time, school officials again presented the letter, but the soldiers fired their guns toward the assembled teachers and students, who fled.

But in 2015 Afghanistan endorsed the Safe Schools Declaration, an inter-governmental political commitment countries make to protect students, teachers, schools and universities from attack during times of war. The declaration includes a commitment for armed forces to refrain from using schools for military purposes, such as for bases or barracks.

Since endorsing the declaration, Afghanistan’s Ministry of Education has been using it to try to persuade security forces to end this practice of endangering schools and students by using schools for military purposes. In the years since, the number of schools documented by the United Nations as being used for military purposes in Afghanistan has declined, although the practice has by no means ended.

Countries that join the Safe Schools Declaration agree to restore access to education faster when schools are attacked, and to make it less likely that students, teachers and schools will be attacked in the first place. They seek to deter such attacks by promising to investigate and prosecute war crimes involving schools. And they agree to minimize the use of schools for military purposes, so they don’t become targets for attack.

But Japan isn’t among the 73 countries — more than a third of the world — that have already joined the Safe Schools Declaration. This is the case even though United Nations Secretary-General Antonio Guterres has called on all countries to do so. And despite a 2015 U.N. Security Council resolution calling on all countries to take concrete measures to deter military use of schools.

The Safe Schools Declaration also builds a community of nations committed to respecting the civilian nature of schools and developing and sharing examples of good practices for protecting schools during war.

If Japan were to join this community by endorsing the declaration, it could provide stronger support for the Afghan education ministry in its efforts to ensure that all schools — including those financed by Japanese taxpayers — are used for their stated purpose of education, rather than turned into part of the battlefield.

As Japan’s children return to school this week, the government should reach out to children around the world by endorsing the Safe Schools Declaration.

Kanae Doi is the Japan director at Human Rights Watch.