Definition: In this task, you will be presented with a passage and have to answer a question based on your understanding of the events inferred from the passage. Try to find the best answer that is most likely to fill in "_". Note that the URLs in the text have been replaced with [Link].
Input: Seoul, South Korea (CNN) -- North Korea on Monday fired more projectiles into the sea off its east coast, South Korean officials said, urging Pyongyang to refrain from "tension-creating acts." But Pyongyang described the launches as a "regular military exercise." The South Korean Defense Ministry still needs to analyze exactly what the North has been firing for the past three days, said Choi Yong-su, an official in the ministry representative's office. They could be short-range missiles or a new kind of large-caliber artillery rocket, the ministry said. The North fired three projectiles into waters off its east coast Saturday and a fourth Sunday. It fired two more Monday, Choi said.North Korea says the launches are a "regular military exercise"North Korea has fired six projectiles into the sea over the past three days, Seoul saysThe South says they could be short-range missiles or large-scale artilleryThe North last week criticized the presence of a U.S. aircraft carrier in the region 
 Question:Before last week, tensions in the region had eased from a period in March and April that included near daily _ threats of war against South Korea and the United States.

North Korea