Defense Minister Panos Kammenos defended his decision to sign and re-activate a 500-million-euro contract to upgrade five P-3B Orion aircraft.

The story saw the light of day in Sunday’s Proto Thema and has stirred controversy, bearing in mind the fact that this is the largest weapons-related outlay in the last decade and comes at a time when Greece is struggling financially.

Kammenos said the modernization of the aircraft was key to Greece’s participation in NATO surveillance missions, and which have been rubber-stamped by two separate inner-cabinet meetings.

Speaking to to a late-night current affairs program on the private STAR TV channel, he said: “The program expired on Dec. 31, 2014, and (former defense minister Nikos) Dendias had requested a three-month extension to the contract.”

Kammenos said he had no choice but to either sign or refuse, as the agreement was reaching its deadline. “We signed, because we couldn’t allow Turkish aircraft to take part in search and rescue operations at the Aegean Sea,” he said.

The 35-year-old aircraft are currently grounded, however, they reportedly meet requirements necessary to take part in NATO collaborations after they are modernized.

The contract signed on March 15 by the Radical Left Coalition (SYRIZA) and the Independent Greeks (ANEL) junior partner was part of a decision that had been agreed upon on October 13, 2014, with exactly the same terms. He pointed to signatories such as former prime minister Antonis Samaras, former deputy prime minister Evangelos Venizelos, former finance minister Gikas Hardouvelis and former administration minister Kyriakos Mitsotakis.

The fact that the contract was directly handed to Lockheed Martin was raised in Parliament by the centrist Potami party, sparking criticism by other members of the opposition as well as members of the ruling SYRIZA party.

SYRIZA MEP Costas Chrysogonos, amongst others, voiced reservations concerning the timing of the expenditure.