Russian President Vladimir Putin and North Korean leader Kim Jong Un have signed a new partnership that includes a vow of mutual aid if either country is attacked.

The deal was struck Wednesday during a summit that came as both face escalating standoffs with the West.

The details of the partnership were not immediately clear, but both leaders have described it as a major upgrade of their ties.

It could mark the strongest connection between Moscow and Pyongyang since the Soviet Union collapsed in 1991.

Putin is visiting North Korea for the first time in 24 years.