US military intelligence-gathering flights are surging off the coast of Cuba, a CNN analysis of publicly available aviation data shows.

Since February 4, the US Navy and Air Force have conducted at least 25 such flights using manned aircraft and drones, most of them near the country’s two biggest cities, Havana and Santiago de Cuba, and some coming within 40 miles of the coast, according to FlightRadar24.

Most of the flights were by P-8A Poseidon maritime patrol aircraft, which are designed for surveillance and reconnaissance, while some were by an RC-135V Rivet Joint, which specializes in signals intelligence gathering. Several MQ-4C Triton high-altitude reconnaissance drones have also been used.