BRUSSELS, June 27. /TASS/. NATO and Russia must preserve lines of communications but a broad dialogue between them is no longer possible as Moscow will be named the most significant threat to the alliance when its members convene for a summit in Madrid, NATO’s Secretary General Jens Stoltenberg said on Monday.

"Our new concept will guide us in an era of strategic competition," he said at a news conference ahead of the summit taking place on June 28-30. "I expect it will make clear that allies consider Russia as the most significant and direct threat to our security."

The official said partnership and dialogue between Russia and NATO are no longer possible.

"Russia’s walked away from the partnership and the dialog that NATO had tried to establish with Russia for many years," he said. "The meaningful dialog we worked for for so many years - that’s not on the table."

But the official said lines of communications should remain.

"There’s a need to have lines of communications to prevent incidents and accidents and also at some stage, hopefully, be able to engage in some kind of weapons control efforts," he said.

Regarding Kaliningrad, Stoltenberg said he was sure Russia is aware that the alliance is ready to defend Lithuania.

"I’m confident that Moscow, President [of Russia Vladimir] Putin understands our collective security guarantees, understands the consequence of attacking a NATO allied country it will trigger response from the whole alliance," he said. "That’s the main message: that we will defend, and by sending that message clearly we are actually preventing an attack."

Stoltenberg said NATO is concerned about Russia’s military presence in Kaliningrad. The official said Lithuania is following EU sanctions that NATO supports.

A NATO summit is scheduled for June 28-30 in the Spanish capital. It will adopt a new strategic concept, consider strengthening the alliance and the consequences of global climate change for security.