The agreement signed in Washington marks a deepening of US relations with a longstanding European ally despite a growing focus by President Joe Biden's administration on Asia.

Greece and the United States signed a five-year extension of the Mutual Defense Cooperation Agreement, which has been renewed each year since 1990, with an understanding it will remain in force indefinitely afterward unless either country gives a two-year notice.

The extension also continues an expansion of access in Greece for US troops, whose key hub is the NATO base at Souda Bay.

Signing the agreement, Secretary of State Antony Blinken called Greece "a strong and reliable ally" and pointed to the NATO partner's assistance in Afghanistan.

Neither Blinken nor Greek Foreign Minister Nikos Dendias explicitly mentioned Turkey but Athens last year launched an ambitious program to buy weapons after a maritime standoff with the fellow NATO ally.

"In the Eastern Mediterranean," Dendias said, "Greece is facing a casus belli, a threat with war if it exercises its sovereign rights and, I have to say, Greece is facing daily provocation."

"Greece is committed to resolve disputes with diplomacy and always in accordance with international law," he said.

He voiced appreciation for the US commitment, saying, "We understand that the United States is increasingly preoccupied with challenges on other parts of the world."

The Greek parliament a week earlier ratified a major defense agreement with France, with Athens buying three frigates at a cost of three billion euros ($3.5 billion).

The deal was announced as France is still smarting over the loss of a major submarine contract with Australia, which said it needed US nuclear technology amid rising tension with China.

Dendias said the agreement with France will "contribute to enhancing the European pillar of NATO" and will promote "fairer burden-sharing between the two sides of the Atlantic."

Tensions soared last year when Turkey sent an exploration ship and small navy flotilla to conduct research in waters which Greece considers its own under treaties.

Turkish President Recep Tayyip Erdogan recently also endorsed a formal partition of Cyprus, which Ankara invaded in 1974 in response to a coup engineered by Greece's then military junta.