North Korea seems to have taken "initial steps" to deploy mobile long-range missiles, the head of the U.S. intelligence community said Tuesday, as the unpredictable communist nation churns out military threats.

"Last April it displayed what appears to be a rogue mobile intercontinental ballistic missile," James Clapper, director of National Intelligence, said at a Senate hearing on national security challenges. "We believe North Korea has already taken initial steps towards fielding this system, although it remains untested."

He was apparently talking about North Korea's military parade in April last year, in which what seems to be a new long-range missile was made public.

Clapper, formerly an Air Force general, has long worked in the intelligence sector. In the 1980s, he worked as director of intelligence for U.S. Forces Korea.

He expressed concern about Pyongyang's recent bellicose statements. It has warned of a "pre-emptive nuclear strike" against South Korea and the U.S. and the nullification of the 1953 Armistice Agreement, which has served as a basic tool for shaky peace on the peninsula for decades.

"The rhetoric, while it is propaganda laced, is also an indicator of their attitude and perhaps their intent," Clapper said. "So for my part I am very concerned about what they might do and they are certainly, if they chose -- so chose could initiative a provocative action against the South."

In an annual report to Congress submitted earlier, Clapper said the North may attempt to use nuclear weapons against the U.S. if its leadership, led by Kim Jong-un, known to be in his late 20s, feels a threat to its survival.

"Although we assess with low confidence that the North would only attempt to use nuclear weapons against U.S. forces or allies to preserve the Kim regime, we do not know what would constitute, from the North's perspective, crossing that threshold," he said in the report on global security issues. "We do not know Pyongyang's nuclear doctrine or employment concepts."

The possibilities of North Korea launching a nuclear-tipped ballistic missile towards the U.S. or its allies have drawn keen attention in the U.S. capital in recent weeks.

North Korea apparently conducted a successful nuclear test last month in the wake of managing to launch space rocket in December.

"North Korea has already demonstrated capabilities that threaten the United States and the security environment in East Asia," Clapper said.

U.S. government officials state they are confident of defending their homeland against any ballistic missile attacks.

"What I can say is we are confident we could defeat a threat from North Korea today," Gen. Robert Kehler, commander of U.S. Strategic Command, said at a separate congressional hearing. "But given the potential progress we are seeing from them, we are considering right now whether we need to take additional steps."

Asked about whether the U.S. has sufficient missile defense assets, he said yes if those are to counter a "limited attack."

The Obama administration has postponed plans to increase the number of ground-based interceptors in the U.S. to 44 from the current 30.

"I am satisfied that we can defend against a limited attack from North Korea today with 30," Kehler said.

He stressed that his troops will be ready for any decision by President Barack Obama to deal with the North Korea crisis.

"What I would say is that deterring North Korea from acting irrationally is our No. 1 priority," he said. "And today, my assessment of certainly Strategic Command's role in this is that we are capable of offering to the president a full range of options.

Whatever he chooses to use in response to a North Korea act, I believe we can make available to him and I am confident in that today."

Meanwhile, the State Department once again called for Pyongyang to avert its confrontational stance.

If it is willing to abide by international rules and obligations, it can have a better future for its people, said department spokeswoman Victoria Nuland.

"This kind of trash-talking is not going to take them there," she told reporters.

Speaking at the Asia Society in New York on Monday, U.S.

National Security Adviser Tom Donilon said Obama came to office "willing to offer his hand to those who would unclench their fists."

"The United States is prepared to sit down with North Korea to negotiate and to implement the commitments that they and the United States have made," he said. "We ask only that Pyongyang prove its seriousness by taking meaningful steps to show it will abide by its commitments, honor its words, and respect international law." (Yonhap News)