FILE PHOTO - Military vehicles carry missiles with characters reading 'Pukkuksong' during a military parade marking the 105th birth anniversary of North Korea's founding father, Kim Il Sung, in Pyongyang, April 15, 2017. REUTERS/Sue-Lin Wong/File photo

WASHINGTON (Reuters) - The head of the U.S. Missile Defense Agency, Vice Admiral James Syring, said on Wednesday that technological advances demonstrated by North Korea in its ballistic missile program in the past six months had caused him “great concern.”

Syring told a hearing of the U.S. House Armed Services Committee that it was incumbent on his agency to assume that North Korea today could “range” the United States with an intercontinental ballistic missile carrying a nuclear warhead.

“I would not say we are comfortably ahead of the threat; I would say we are addressing the threat that we know today,” Syring said.

“The advancements in the last six months have caused great concern to me and others, in the advancement of and demonstration of technology of ballistic missiles from North Korea.

“It is incumbent on us to assume that North Korea today can range the United States with an ICBM carrying a nuclear warhead.”

North Korea has conducted dozens of missile tests since the start of last year, as well as its fourth and fifth nuclear bomb tests.

It has said it is working to develop a nuclear-tipped ICBM capable of reaching the U.S. mainland, presenting U.S. President Donald Trump with perhaps his most pressing security threat.

Missile experts say North Korea could soon test its first ICBM, but believe it will take until at least 2020 before it is capable of fielding an operational nuclear-tipped ICBM.