North Korea may be able to develop a submarine-based ballistic missile within a year, which would significantly increase the threat Pyongyang poses, a US expert said Wednesday.

The North Koreans "will attempt or succeed in a full-range test some time in the next 12 months," Joseph Bermudez of Johns Hopkins University's US-Korea Institute in Washington said.

Pyongyang may also develop a submarine missile launcher capable of firing eight to 12 rockets by 2020, he added.

North Korea has carried out a series of submarine-launched missile (SLBM) tests since 2014.

The latest took place last week, when a missile fired from a submarine reached an altitude of around 33,000 feet (10,000 meters) before exploding during the first phase of its flight.

Although such missiles' exact range is unknown, it would be less than 2,500 miles (4,000 kilometers), based on estimates of the rocket size, Bermudez said.

The capability to fire missiles from submarines instead of fixed installations would present Washington and its regional allies with significant challenges, he added.

"The threat is in its initial stages and it has the real capability to become a significant threat going forward," Bermudez said.

Tensions on the Korean Peninsula have escalated since North Korea staged a fourth nuclear test in January.

Pyongyang has also stepped up its missile tests.

Experts believe the country is advancing its efforts to develop an intercontinental ballistic missile capable of launching a nuclear attack on the US continent.

The United States last week announced plans to deploy an advanced missile defense system in South Korea.

Washington also put North Korean leader Kim Jong-Un on its sanctions blacklist, accusing him of being directly responsible for a long list of serious human rights abuses.

Pyongyang called the measure a "declaration of war."