US Secretary of State Hillary Clinton said Thursday that US-backed plans for a European missile shield should be no cause for counter-measures, after Russia threatened to deploy missiles near Europe.

"We will continue to press forward on missile defence," Clinton told a press conference in Brussels after talks between NATO foreign ministers and their Russian counterpart Sergei Lavrov.

"It is certainly not a cause for military counter-measures," she said.

Seeking to ease Kremlin concerns that the system is directed at Russia's strategic nuclear deterrent, Clinton said it was aimed at countering a threat emanating from Iran.

"This is not directed at Russia, it is not about Russia. It is frankly about Iran and other state or non-state actors who are seeking to develop threatening missile technology," she said.

The NATO and Russian ministers failed to resolve their disagreement over the missile shield being built with US technology to protect Europe from ballistic missile threats, but they agreed to continue talks on potential cooperation.