The US is considering sending ground troops to the Baltic states on new military exercises as it seeks to reassure Nato allies in eastern Europe of its commitment to preventing further territorial incursion by Russia.

Vice president Joe Biden spoke of the plan during a meeting with the Estonian president Toomas Ilves after calls for a tougher US response to Russia’s attempted annexation of the Crimea.

It follows a Pentagon announcement of extra US F-15 jets to join Nato patrols in Poland and the Baltic on March 5, and recent requests by the Ukrainian government for possible US military assistance outside the Nato area.

“We are exploring a number of additional steps to increase the pace and scope of our military co-operation, including rotating US forces to the Baltic region to conduct ground and naval exercises – as well as training missions,” said Biden.

President Ilves called on Nato to put “the east-west relationship on a new standing” after events in the Ukraine.

“The old idea of Nato predicated on a Europe that no longer has any threats has unfortunately turned out no longer to apply,” he told Biden.

“We in Nato must draw our conclusions from Russia’s behaviour in the current crisis and conduct a review of the entire range of Nato-Russia relations. My hope is that at the upcoming [Nato] summit in Wales we will refocus on common defence: the raison d’etre of the alliance.”

Biden, also visited Warsaw where he reportedly told Polish president Bronislaw Komorowski that the US had sent a dozen F-16s to a Polish base, and will expand army trainers to help the Polish army modernise.

“You have an ally whose budget is larger than the next 10 nations in the world combined, so don’t worry about where we are,” Biden told Komorowski, according to a White House pool report.

The US vice-president will visit Lithuania on Wednesday.

The White House said it was also considering calls for military assistance from the Ukraine, which is not a Nato member but is thought to have asked for defence equipment.

“We are reviewing requests by the Ukrainian government and will continue to do that, our focus remains however on economic and diplomatic efforts aimed at de-escalating the situation in the Ukraine,” said spokesman Jay Carney.

Carney rejected continued criticism of the US response so far, which has mainly focused on financial sanctions and visa bans on Russian and Ukrainian officials.

“More is coming. Work is being done to make further designations,” said Carney. “There will be further costs involved not just by the United States, but by others.”

Biden also promised further attempts to reduce European dependence on Russian gas during his visits to Poland and Estonia.

“As we discussed today, we are working to create greater economic co-operation to diversify your sources of energy,” he told Ilves.