6 navy ships protects Britain's shores...
They know about all the air flights into and out of the UK...but not boats...
Lord West was giving evidence as the committee investigates Britain's defences against terrorism.
The minister also disclosed his concerns about the monitoring of Britain's coastline by the Royal Navy and other authorities.
There are only six navy ships permanently assigned to patrol the 11,000 miles of the British coast, the committee heard.
Lord West, a former admiral, said that there is no way for the UK authorities to track every vessel entering British waters.
"We are not able to monitor all traffic in our waters. It is not what I would call, ultimately, satisfactory," he said.
"When you look into the sky, generally, we pretty well know what is moving. We don't know that around our waters.
"I think it would be quite a good thing to have a very good picture of what is moving around our coast."
James Arbuthnot, the Tory chair of the defence committee, said he was listening the minister's answers "with increasing horror."