At least three American reconnaissance aircraft were spotted near Russia’s southern and western borders on 1 May, the online aircraft monitoring resource PlaneRadarreports.

A US Air Force Boeing RC-135V, a large reconnaissance aircraft based in the UK, flew near the Russian exclave of Kaliningrad on the Baltic Sea at 12:00 Moscow time, travelling at 692 kilometres per hour.

The plane made its reconnaissance flight at an altitude of almost eight kilometres.

In addition, a US Navy P-8A Poseidon anti-submarine patrol aircraft took off from NATO’s Sigonella base in Sicily, Italy on Tuesday, and made its way to the vicinity of Novorossiysk, a Russian port city on the Black Sea.

Shortly after, the plane conducted a three-hour reconnaissance flight near Crimea’s southern borders, moving at a speed of almost 567 kilometres per hour at an altitude of about 4.6 kilometres.

Separately, a US Air Force RQ-4B-40 Global Hawk drone took off from a base in Italy and flew near eastern Ukraine's Donbass region before heading to Russia’s Black Sea coast.

Tuesday’s flights were the latest in a series of such missions carried out by the US military in the past few months. 

The US and NATO have substantially increased their reconnaissance operations along Russia's borders in the Black and Baltic Seas, as well as around Russian military facilities in Syria, in recent years.

The past year has seen 3,000 foreign combat aircraft, including about 1,000 spy planes, flying near Russia's maritime and land borders. The Russian Defence Ministry has repeatedly called on the Pentagon to put an end to such flights; however, these requests were dismissed by Washington.