The Americans were to be housed in a Ukrainian defence ministry sanatorium in the southern Crimean village of Partenit while they prepared for military exercises designed to develop military cooperation between Ukraine and NATO.

But an anti-NATO demonstration blocked the road to the village, and the US troops had to be housed in a different sanatorium some distance away in Alushta.

The preparations for the Sea Breeze 2006 military manoeuvres involving NATO members and their former Cold-War Warsaw Pact enemies, now participants in NATO's Partnership for Peace, have met with a great deal of opposition in Ukraine.

The country's pro-Western President, Viktor Yushchenko, wants Ukraine to join NATO eventually, but a large section of the population is opposed to that goal.

The former Soviet country is split between those who favour maintaining a special relationship with Russia and those who want to forge closer ties with Western institutions.

The pro-Russian Regions party came top in parliamentary elections held on March 26, but has not been able to form a government. The Communist party, well represented at the Crimea demonstrations, is also staunchly pro-Russian.

Hostility to the North Atlantic alliance is particularly strong in Crimea, where the Russian Black Sea fleet is based.

Also on the initiative of Ukraine's pro-Russian parties, several dozen people have been blocking the port of Feodosia in eastern Crimea in protest at the arrival of a US ship carrying military materials.

And there have been demonstrations at the nearby Starokrymsky training facility, where the Sea Breeze exercises are due to take place, Interfax reported.