Growth-at-all-costs was the signal from China behind the iron ore rally

Be careful betting against iron ore, BMO says. Goldman disagrees.

Metals analysts at BMO have weighed in on today's rip in iron ore prices. They say the trigger was optimism about growth from Chinese leaders.

"Growth all any costs is back on the table," wrote analyst Jessica Fung.

She also notes that some supplies have been choked this year by weather in Australia and Brazil.

Separately, Bloomberg notes that iron ore short interest rose 210% in 2016. That's a good sign that a short squeeze is underway. Analysts at Goldman Sachs don't believe the gains will last because there is a lack of real demand.

I think the debate about what's happening today is bizarre. It's obviously a short squeeze. Commodity markets don't move 20% in a day unless someone is getting blown up (in the market or in a war).