A man watches a TV showing a file image of a North Korea's missile launch Tuesday during a news program at the Seoul Railway Station in Seoul, South Korea. North Korea on Tuesday continued to ramp up its weapons demonstrations by firing unidentified projectiles twice into the sea while lashing out at the United States and South Korea for continuing their joint military exercises that the North says could derail fragile nuclear diplomacy. The sign reads "North Korea could seek a new road." Credit: Ahn Young-joon | AP

North Korea fired more projectiles into the waters off its coastline and questioned the value of talks with the U.S., adding more pressure on President Donald Trump just as his trade war with China escalates.

For the fourth time in the last two weeks, Kim Jong Un’s regime shot unidentified projectiles into the waters between the Korean Peninsula and Japan, South Korea’s defense ministry said in a statement. They originated in South Hwanghae province, just north of Seoul, the ministry said.

North Korea separately denounced U.S.-South Korean joint military exercises that kicked off Monday, calling them an “undisguised denial and a flagrant violation” of the agreement reached during last year’s meeting in Singapore between Kim and Trump. The situation is “dramatically dampening” North Korea’s desire to implement those agreements and could affect future dialogue, it said.

“The U.S. and South Korean authorities remain outwardly talkative about dialogue, but when they sit back they sharpen a sword to do us harm,” the North Korean foreign ministry said in a statement via the official Korean Central News Agency. The U.S. and South Korea will “pay a heavy price” if they continue to ignore North Korea’s warnings, it said.

Tensions have continued to rise ever since Trump met Kim last month at the demilitarized zone separating the two Koreas and became the first sitting American president to step foot in North Korea. Talks on North Korea’s nuclear program remain stuck, with the U.S. rejecting Kim’s offer to dismantle the main Yongbyon nuclear complex in return for sanctions relief.

North Korea has so far avoided conducting nuclear tests or firing intercontinental ballistic missiles that can reach the U.S. mainland. Trump has repeatedly dismissed the importance of short-range missile tests, and said last week that Kim “does not want to disappoint his friend, President Trump!”