The F-15E jets arrived at the Amari base in northwest Estonia to take part in an exercise along with four Danish jets due to arrive in Lithuania on Thursday.

"The additional aircraft will work closely with the current detachments to increase our readiness, build crucial interoperability and underline the robust solidarity across the Alliance," Major General Joerg Lebert, Chief of Staff at Headquarters Allied Air Command in Germany, said in a statement.

The exercise is taking place after Estonian Prime Minister Kaja Kallas called for a greater US presence in the Baltic states in order to deter Russia.

Following Russia's annexation of Crimea in 2014, NATO set up a Baltic air policing mission and placed multinational battle groups in the three Baltic states and Poland.

All four countries were once part of the Soviet bloc.

Russia has demanded in recent weeks that forces from other NATO countries should be pulled back from the Western military alliance's eastern flank.