South Korea has claimed North Korea carried out large-scale military drills to mark the anniversary of the country's army.
A statement from South Korean military said live-fire exercises had taken place in the Wonsan region on Tuesday, but did not specify on further details - like what kind of weapons had been tested.
The alleged tests would coincide with exercises conducted by the US and South Korean navies off the coast of the Korean peninsula, and the docking of US submarines in Seoul - in what US officials called "a show of force."
This comes amid mounting tension in the region as North Korea refuses to abandon its nuclear program.
Having already conducted several nuclear tests, the country recently paraded its ballistic missles through Pyongyang as a show of force to coincide with its Day of the Sun celebrations. However another missile test, again carried out to coincide with Day of the Sun, ended in failure.
The ceremony, and missile test, occurred at the same time US president Donald Trump sent a US taskforce to the Korean peninsula as a precaution.
North Korea and its leader Kim Jong-un have defiantly warned the US they will respond with "all-out war" if there is even the slightest indication of an attack.