NATO Secretary-General, Jens Stoltenberg says he will raise the "challenge" of "new Russian missiles which are putting the INF Treaty in jeopardy."
The Intermediate-Range Nuclear Forces Treaty (INF) was signed in 1987 between Russia and the United States to significantly cut the nuclear weapons capabilities of both sides around Europe.
Speaking on Tuesday, Mr Stoltenberg confirmed that Russia had been acting outside the confines of the US and Russia's nuclear treaty.
He said: "Russia has developed, tested and also fielded new missiles, SSC-8, for years."
"These missiles are mobile, hard to detect, nuclear-capable and they are putting the INF Treaty in jeopardy."
But he defended the US, saying they had complied to the treaty and that it was only Russia who had been acting outside its boundaries.
"The United States is in full compliance with the INF Treaty, there are no new US missiles in Europe, but there are new Russian missiles in Europe, and therefore we should all call on Russia to ensure full and transparent compliance with the INF Treaty.
"We don’t want a new arms race and the INF Treaty has been important for our security for decades."
Following the revelations that Russia had been developing missiles, US President Donald Trump has said he will pull out of the INF treaty.
Mr Trump said the United States will increase its nuclear arsenal "until people come to their senses".
But the Kremlin denies breaking the treaty.
In October, Donald Trump said: "Until people come to their senses, we will build it up.
"Russia has not adhered to the agreement. This should’ve been done years ago."