With current plans still on the table for the Pentagon to send a warship into the Black Sea, we could be witnessing the build-up to a yet further major incident which could easily lead to war.

The Pentagon confirmed Thursday it conducted a provocative military reconnaissance flyover of Ukraine following heightened tensions in the wake of the Nov. 25 Kerch Strait incident. 

Air Force OC-135B Open Skies observation jet, via Military.com

A Pentagon official stated the rare flight was carried out under the international Open Skies Treaty to “reaffirm U.S. commitment to Ukraine," according to the Wall Street Journal. The specific flight path is unknown, but an unarmed high-tech Air Force observation plane was used with international personnel on board, likely to signal international opposition to what the US has called Russian "aggression" around Crimea in the Black Sea, per the WSJ report:

U.S. officials wouldn’t specify the Thursday plane’s flight path but said it was near Crimea, the Ukrainian region seized by Russia in a 2014 invasion. They used a U.S. Air Force OC-135 observation plane, which was specifically designed for such missions, with U.S., Canadian, German, French, UK, Romanian and Ukrainian observers aboard, the Pentagon said.

This also comes after the US notified Turkey that it may send a warship through the key Bosporus Straits and Dardanelles waterways in order to enter the Black Sea for the first time since the Russian seizure of three Ukrainian vessels near the Kerch Strait. US defense officials weren't shy to note that the request was specifically in response to Russia's actions against Ukraine.

But also on Wednesday in the most significant US-Russia incident an American destroyer sailed through waters claimed by Russia in the Sea of Japan for the first time since the Soviet era in 1987. The U.S. Pacific Fleet confirmed that the guided-missile destroyer USS McCampbell sailed “in the vicinity of” Peter the Great Bay on Wednesday — a body of water off the Russian port city of Vladivostok — in order to “challenge Russia's excessive maritime claims and uphold the rights, freedoms and lawful uses of the sea enjoyed by the United States and other nations,” according to a Navy official statement.

In a statement reported by Bloomberg the Russian Defense Ministry (MoD) said its own warship and aircraft had escorted the American destroyer as it sailed near the contested waters. The MoD emphasized the USS McCampbell didn’t enter to within 100 kilometers (60 miles) to Russian territorial waters. The Russian military statement framed the US destroyer's reaction as one of attempting "to escape at full speed" from the Russian escort vessel.

Thursday's US flyover of Ukraine is the second significant provocative maneuver in as many days, and further comes days after the Kremlin announced it is transferring more S-400 anti-air missile defense systems to Crimea. 

Following the observation flight over Ukraine, the Pentagon issued a statement, which reads:

“Russia’s unprovoked attack on Ukrainian naval vessels in the Black Sea near the Kerch Strait is a dangerous escalation in a pattern of increasingly provocative and threatening activity.”

It further slammed Russia's "destabilizing" actions, adding:

“The United States seeks a better relationship with Russia, but this cannot happen while its unlawful and destabilizing actions continue in Ukraine and elsewhere.”

With current plans still on the table for the Pentagon to send a warship into the Black Sea, we could be witnessing the build-up to a yet further major incident which could easily lead to war.