U.S. Ambassador to the United Nations Nikki Haley claims recovered parts of a missile are tied to Iran.
A recent report alleged North Korea was developing submarines capable of launching ballistic missiles.
The New York Times reports China might expect refugees to rush across the river separating the countries.
Japan's defense minister said the missiles would be used to defend naval ships and possibly for island defense.
The two prominent Islamic countries are locked in a Cold War-like struggle for regional dominance.
Iran's president said Sunday that the country will continue making missiles.
U.S. President Donald Trump warned in a brief statement Tuesday that "all options are on the table" when it comes to Pyongyang.
The U.S. conducted a missile defense test over the Pacific Ocean just two days after North Korea launched an intercontinental ballistic missile.
The launch came a day after President Trump said there's a chance of a "major conflict" with North Korea.
North Korea celebrated the anniversary of the founding of its military Tuesday by conducting a huge, long-range artillery drill.
North Korea launched a ballistic missile into the Sea of Japan, just days before President Donald Trump and Chinese President Xi Jinping will meet.
Days after Kim Jong Un orderered weapons tests, North Korea has fired another ballistic missile into the sea.