Guided-missile destroyer USS Porter (DDG-78) entered the Black Sea on Thursday and is the sixth U.S. ship to operate in the region this year.

Porter, one of four U.S. destroyers based in Spain, moved across the Bosphorus and into the Black Sea, according to Turkish ship spotters.

It’s the first U.S. ship to operate in the Black Sea since the Spearhead-class USNS Yuma (T-EPF-8) left the region in late July after the joint U.S.- Ukraine Sea Breeze 2019 exercise.

In a statement, U.S. 6th Fleet did not tie the deployment to a specific exercise.

“The naval operations we conduct in the Black Sea with our allies and partners maintain the strong relationships that are necessary for regional stability,” Vice Adm. Lisa M. Franchetti, the commander of 6th Fleet, said in a statement. “The inherent flexibility of our forward-deployed naval force DDGs enables our ability to provide a credible defense and ensure we are postured appropriately to support our global operations.”

The four destroyers in Rota are part of the U.S. phased European adaptive approach to ballistic missile defense that pairs the capabilities of the destroyers with Aegis Ashore BMD stations in Poland and Romania.

The Navy has stepped up its presence in the Mediterranean and the Black Sea since the 2014 invasion of Crimea by Russia.

The following is the complete statement from U.S. 6th Fleet.

The Arleigh Burke-class guided-missile destroyer USS Porter (DDG-78) began its north-bound transit to the Black Sea August 8, 2019, to enhance regional maritime stability and a show of support for our NATO allies and partners in the region.

This is the sixth time a U.S. ship has visited the Black Sea since the beginning of 2019. The last ship to visit the Black Sea was USS Carney in July. During its time in the Black Sea, USS Carney (DDG-64) participated in exercise Sea Breeze 2019, a U.S.-Ukraine co-hosted exercise that brought 19 nations together for the 19th iteration of the exercise.

“The naval operations we conduct in the Black Sea with our allies and partners maintain the strong relationships that are necessary for regional stability,” said Vice Adm. Lisa M. Franchetti, commander of U.S. 6th Fleet. “The inherent flexibility of our forward-deployed naval force DDGs enables our ability to provide a credible defense and ensure we are postured appropriately to support our global operations.”

Porter, forward-deployed at Naval Station Rota, Spain, is conducting naval operations in the U.S. 6th Fleet area of operations in support of U.S. national security interests in Europe. The U.S. Navy routinely operates in the Black Sea consistent with international law, as well as with the Montreux Convention.

U.S. 6th Fleet, headquartered in Naples, Italy, conducts the full spectrum of joint and naval operations, often in concert with allied, and interagency partners, in order to advance U.S. national interests and security and stability in Europe and Africa.