"Denmark is a small country, it is coming under strong pressure," Putin said in televised comments at an energy forum in Moscow. "It's up to (Denmark) whether it's able to demonstrate its independence and show it has sovereignty. If not, there are other routes," he added. "It will be more expensive and will push us back a bit, but I think the project will be completed."
Gazprom chairman Viktor Zubkov said earlier Wednesday at the same forum that if Denmark refused permission, the pipeline could bypass that area of sea. "If they don't approve it... we will go around Denmark's economic zone," he said, quoted by state news agency TASS.
The energy link will double the capacity to ship gas between Russia and Germany, sparking concerns about Western Europe's increasing dependence on Russian gas. It has also raised fears that Moscow will be able to increase pressure on Ukraine, as Europe will be less reliant on the country for transiting supplies.
Its proponents - led by Germany, the EU's biggest economy - say the pipeline will provide reliable supplies at an acceptable price. US President Donald Trump however has threatened to hit Nord Stream 2 and those tied to it with sanctions, saying it makes Germany "a hostage to Russia."
"The US unfortunately has always been against our cooperation on energy with Europe," Putin said Wednesday. Zubkov said the pipeline would provide "gas for Europe". Gazprom said on Tuesday that the pipeline was 83-percent complete, with more than 2,000 kilometres (1,240 miles) laid.