Japan plans to avoid expressing direct support for actual U.S. military action against Syria, in an attempt to avoid damaging negotiations with Russia over a decadeslong territorial row, government sources said Thursday.

Japan will only support U.S. President Donald Trump's "resolve" to prevent any further use of chemical weapons in Syria, the sources said.

Russia is a major backer of the government of Syrian President Bashar al-Assad in the country's civil war, and strongly opposes the U.S. claim that Syrian government forces attacked a rebel-held town near Damascus on Saturday with chemical weapons.