US must keep 'nuclear triad' defence system, Pentagon chief says
The United States must keep all three parts of its nuclear force, rather than eliminate one, US Defence Secretary Jim Mattis said despite previous remarks suggesting he was favourable to change.
Some argue ground-based missiles may no longer be necessary to Washington's policy of deterrence, and the Trump administration has been reviewing the military's nuclear posture.
Mr Mattis has called the submarine-based component "sacrosanct" and has said it is necessary to retain the ability to fire nuclear weapons from planes.
Together, those three prongs constitute what the military calls its nuclear triad.
Before he took over in January as President Donald Trump's Pentagon chief, Mr Mattis had suggested that long-range, silo-based weapons, known as intercontinental ballistic missiles (ICBMs), might be expendable.
"I've questioned the triad," Mr Mattis told reporters flying with him to Minot Air Force Base, a nuclear base in northwestern North Dakota.
He said his view has changed.
"I cannot solve the deterrent problem reducing it from a triad.
"If I want to send the most compelling message, I have been persuaded that the triad in its framework is the right way to go," Mr Mattis said.
Mr Mattis has previously indicated this evolution in thinking, but his statements Wednesday were emphatic.
The key to avoiding nuclear war, he said, is maintaining a nuclear arsenal sufficient to convince a potential enemy that attacking the US with a nuclear weapon would be suicidal.
"You want the enemy to look at it and say, this is impossible to take out in a first strike, and the (US) retaliation is such that we don't want to do it," he said.
"That's how a deterrent works."
Thus the US will keep nuclear missile submarines, land-based nuclear missiles and nuclear-capable aircraft, he indicated.
Mr Mattis also said the Trump administration is reviewing the value of the New Start treaty negotiated with Russia by the Obama administration in 2010.
The treaty, already in effect, requires reductions by both sides to a maximum of 1,550 strategic nuclear warheads by February.