In comments about a Japanese defence report flagging Chinese threats, ministry spokesperson Tan Kefei said the actions have seriously aggravated regional tensions.
A Chinese and a Russian delegation marked the first foreign visits to the country since the Covid-19 pandemic started.
The missile system will have three layers of surface-to-air missiles, which would allow it to hit targets at different ranges.
The launch of real-time missile warning sharing system between the three countries is expected to come into focus during the meeting.
Both India and France have deep interests in the Indian Ocean and are concerned about China’s growing assertiveness in the region.
South Korea has sent various nonlethal aid to Ukraine in its war against Russia's invasion but has rejected Kyiv's requests for lethal weapons.
Myanmar has been in chaos since the military ousted democratically elected civilian leader Aung San Suu Kyi from office in a 2021 coup.
The countries have strengthened ties in recent years, with special focus on defence, as both are concerned over an increasingly assertive China.
Hun Sen ordered members of the armed forces to search for any insurgents who may have entered Cambodia, describing them as “terrorists”.
The response is a result of Cambodia-Vietnam cooperation to prevent anti-Vietnamese government soldiers from taking refuge in Cambodia.