Three Chinese warships have been spotted in international waters off the coast of Australia’s largest city, Sydney, in a rare show of military might that will likely test diplomatic ties between Canberra and Beijing.

Australia and New Zealand are monitoring a group of Chinese naval vessels spotted in international waters near Sydney, the countries’ defence ministers said on Thursday. Three Chinese vessels are traveling down the eastern coast of Australia,

Defence Minister Richard Marles said the vessels did not pose any threats but their presence was an ‘unusual event’.