(CNN) —  

North Korea twice on Tuesday launched unidentified projectiles from South Hwanghae Province toward the waters off the Japanese coast, South Korea’s Joint Chief of Staff (JCS) said in a statement.

“The military is maintaining its readiness by monitoring related movements in preparation for further launches,” the statement said.

A US official told CNN that two short-range ballistic missiles were launched and landed in the Sea of Japan, also known as the East Sea. The official said the missiles are assessed to be the same type as missiles used in recent launches.

“We continue to monitor the situation and are consulting closely with our South Korean and Japanese allies,” a senior administration official said.

Although it made no mention of the launches, North Korea’s Foreign Ministry also issued a statement voicing its displeasure with upcoming joint US-South Korean joint military exercises it called “aggressive.”

Pyongyang would be forced to “seek a new road” if Seoul and Washington were to continue to “sharpen a sword to do us harm,” it said.

Donald Trump said Friday that he had received a “very beautiful” and “very positive” letter from Kim, and shrugged off the significance of North Korea’s missile tests.

North Korea made two launches last week, a senior US official previously told CNN.

The official said US military intelligence tracked a new launch from North Korea on Friday morning local time (Thursday in the United States). According to the initial assessment, the projectile appeared to be similar to the short range ballistic missiles fired earlier this week, the official said, referring to Wednesday’s twin launches from North Korea’s east coast.

US President Donald Trump recently said he had “no problem” with the recent launches.

Asked for his reaction to North Korean ballistic missile testing, he responded: “Short-range missiles. We never made an agreement on that. I have no problem.”