In March, as the North Korean crisis began to heat up, President Obama ordered another 14 interceptors be sent to Greely, bringing its arsenal to 44 from 2017.

"If all it has to worry about is a single missile coming at it, chance it could kill it. If you fire six missiles at one time... and if one gets through, your whole day is ruined.... The problem is sooner or later North Korea will improve its missile ranges, so the question you have to ask is will our anti-missile capabilities make sufficient progress so it could work against a more robust threat?" Sigal said.
"What we've got at Greely is of some limited utility. It's better than nothing," he said.

[link to news.yahoo.com]