(CNN) Two Iranian ships that once appeared to be headed to Venezuela are now in the Baltic Sea approaching the Russian city of St. Petersburg, according to MarineTraffic, a website that tracks ships.
The position of the ships, including the floating military base called the Makran, indicate they are likely headed to St. Petersburg to participate in Russia's Navy Day events, according to two defense officials familiar with the ships' movements.
The Pentagon has been monitoring the ships for about two months as they rounded the southern tip of Africa and appeared set to cross the Atlantic for Venezuela. Pentagon officials were concerned about the potential introduction of Iranian weapons into the Western Hemisphere and the possible transfer of weapons to Venezuela.
In mid-June, the ships, which were then off the coast of West Africa, began to inch north instead of across the Atlantic.
Venezuela's decision to turn away the Iranian ships came after the US applied diplomatic pressure on Caracas and the regime of Nicolas Maduro, two officials said at the time. The US also applied diplomatic pressure to other countries along the route of the Iranian vessels, including countries in West Africa, like Senegal.
The Makran had been seen in late April in satellite images from Maxar Technologies in the port of Bandar Abbas in Iran with seven small fast-attack boats on its deck. A smaller frigate has been accompanying the Makran.
Last month, Pentagon press secretary John Kirby said the delivery of Iranian weapons to the Western Hemisphere would be seen as a "provocative act" and a "threat to our partners." Earlier, Defense Secretary Lloyd Austin had said he was "absolutely concerned" about the proliferation of weapons in the region.
Pentagon officials had been watching to see whether the ships would continue north toward Russia or turn into the Mediterranean Sea and return to Iran. The latter scenario was seen as unlikely because that would appear to be a failure for Iran.
The ship's current position in the Baltic Sea and its direction make its destination clearer, defense officials said. Russia's Navy Day is scheduled for Sunday in St. Petersburg, and it appears the Makran will take part in the events in some way, the officials said.