What are the countries in northeast?
You would have to specify a continent or other region.
The countries in NE North America are Canada and Greenland, part
of Denmark.
The countries in NE South America are Brazil and the Guianas :
Guyana, Suriname, and French Guiana (part of France).
The countries in NE Asia are Russia, China, Japan, and North and
South Korea.
The countries in NE Europe are Poland, Belarus, and Russia, and
the Baltic States of Estonia, Latvia, and Lithuania.
The countries in NE Africa are Libya, Egypt, Chad, Sudan,
Eritrea, Djibouti, Ethiopia, and Somalia, and could include
technically Asian countries of the Middle East : Lebanon, Israel,
Jordan, and the Palestinian state.