North Korea has made at least four previous attempts this year to test this type of missile.

Both missiles were tracked over the Sea of Japan, also known as the East Sea, "where initial indications are they fell," Benham said. Benham said the missile launches did not pose a threat to North America.

Japanese Prime Minister Shinzo Abe said that his country could "never forgive" the test, which he stressed was in violation of U.N. resolutions.

"We can never forgive this and lodged a firm protest," he told reporters from Kumamoto, southern Japan.

"We would like to continue taking a close coordination with the U.S. and South Korea and working on North Korea (at) the United Nations, so that North Korea would not conduct such an action again."

The first missile launch occurred at 5:58 a.m. local time and the South Korean military presumed that one had been a failure, according to a spokesperson from the country's Joint Chiefs of Staff.

About two hours later, North Korea fired the second missile at 8:05 a.m. local time, according to the spokesperson. He said further analysis is being conducted.

The U.S. State Department condemned the recent missile tests in a statement: "We are aware of reports that the DPRK fired two ballistic missiles. We are monitoring and continuing to assess the situation in close coordination with our regional allies and partners."

The United States advised North Korea to stop its ballistic missile tests and said it only strengthened the international community's resolve to press forward with U.N. sanctions. The United States said it would also defend its allies, South Korea and Japan, and called its commitment to them "ironclad."

North Korea tests Musudan again

This year, North Korea has taken much interest in the Musudan, an intermediate-range missile with a strike range of 2,500 to 4,000 kilometers (1,553 to 2485 miles).

"(Kim Jong Un) is interested in being the leader of NK who has been able to create a deliverable nuclear weapon and clearly they're counting on this intermediate range Musudan missile to do that," Christopher Hill, the former U.S. Ambassador to South Korea, told CNN.

"The key element of it is that it's mobile. The fixed launch points, we know precisely where they are, but if this thing pops out a forest we don't."

"The missile didn't reach nearly its full range, but it didn't blow up on the pad and it flew far enough that patient engineers might have learned something from it.

"But as they didn't stop to figure out what went wrong after today's first test, it is pretty clear that they aren't working patiently and trying to learn from their mistakes."

The Musudan missile isn't really new, according to Schilling.

The last several months have been particularly contentious on the Korean peninsula, after North Korea claimed to have tested its first hydrogen bomb, an assertion that U.S. officials dispute, and fired a satellite into orbit.

Why so many missile tests?

North Korea could be testing missiles with such intensity this year due to more financial challenges, said Stephan Haggard, director of the Korea-Pacific program at the University of California San Diego.

"North Korea is on the verge of feeling quite substantial economic distress," Haggard said. "Part of the effort here is to get attention focused back on North Korea, so that perhaps they think they can get some relief from the sanctions instituted recently."

North Korea wants to develop its missiles, because it's a way of delivering nuclear weapons, he said.

"You can develop a nuclear device, but unless you can deliver it, it has no strategic value," he said. Without an air force or a technically capable submarine, the missiles are the only route.

Haggard says nuclear weapons give North Korea's Kim Jong Un leverage to bargain with the rest of the world.

"The farther along they are, the higher bribe price the external community has to pay for them to give it up," he said.

Kim has been in a rush to sharpen North Korea's nuclear and missile capabilities, more so than his father.

In just four years of reign under his son, the younger Kim has now overseen 27 missile launches with the two most recent tests on Wednesday.