Israel is pushing ahead with plans to export its natural gas production from major offshore fields to Greece via Cyprus, defying threats by onetime ally Turkey to use military force to block such moves.

Israel says it has stepped up naval patrols around its largest fields -- Leviathan and Tamar -- in the eastern Mediterranean, which has become an arena of confrontation over the estimated 122 trillion cubic feet of gas the U.S. Geological Survey says lies in the Levant Basin.

Apart from Turkey's threats, Lebanon, which is technically at war with Israel, claims Leviathan lies partly in its waters and has warned it won't allow its hydrocarbon assets to be "plundered."

"One danger is a proximity attack, by frogmen, by boats, by terrorists in some fashion," Israeli former national security adviser Giora Eiland cautioned.

"Another bigger challenge is how to face the threat of missiles."

Leviathan and Tamar contain at least 24.8 tcf but that estimate is expected to increase.

Israeli Deputy Foreign Minister Danny Ayalon is in Greece for two days of talks on joint exploration of the region's gas fields.

These are believed to extend into the territorial waters of Cyprus 150 miles north of Israel, including the southern sector controlled by Greek Cypriots. They're currently exploring the southernmost of their 12 exploration blocks, which abuts Israel's Leviathan and is seen as an extension of that field.

"Greece is a strategically important country due to its proximity to us in the eastern Mediterranean and especially due to the discovery of oil and gas," Ayalon told The Jerusalem Post before heading to Athens.

"We're going to talk about making Greece and Cyprus distribution centers for Israeli gas in Europe, which needs to diversify its sources."

The resource-poor Greek Cypriots, who're aligned with Athens, are reveling in their expected gas boom and are keen to build economic and security relations with Israel, a major military power in the eastern Mediterranean.

Cypriot officials say they envision five projects: a joint underwater pipeline from Israel's gas field to Cyprus, a gas liquefaction plant, a methanol plant, a 1,000-megawatt power station and a strategic reserve, all on the island.

From Cyprus, the plan is for another pipeline to Greece, to funnel the gas into the European Union. Both Greece and the Greek Cypriot state are EU members.

These plans are like a red flag to a bull as far as Turkey, whose Islamist-rooted government is pushing hard make it the paramount power in the region.

The discovery of the gas fields and the tensions they've triggered intersect with two of the region's most intractable conflicts, Turkey's age-old rivalry with Greece and the Arab-Israel conflict.

Cyprus lies between the two. Turkey invaded the island in 1974 following a short-lived coup by supporters of union with Greece. Turkey seized the northern one-third of the island largely inhabited by Turkish Cypriots and declared it the Turkish Republic of Northern Cyprus. Only Ankara recognizes it.

Ankara insists that no exploration can proceed off Cyprus unless it benefits the TRNC as well. It has sent fighter aircraft to the TRNC and launched its own exploration program, protected by Turkish warships.

The Turks are at odds with Israel after the Israelis intercepted a flotilla of foreign ships carrying humanitarian aid to the Israeli-blockaded Gaza Strip May 31, 2010, and killed nine Turks.

Ankara has threatened to use force to prevent Israel and Cyprus from developing the rich gas deposits that could transform their economies and turn them into gas exporters.

So the security issue carries as much weight as the economic and could signal a geostrategic realignment in the region.

Some Greek Cypriots have suggested a security alliance with Israel. The issue has largely been discussed behind closed doors but the Israeli air force recently carried out exercises in Cypriot air space.

Meantime, Israel is extending its gas fields.

Houston company Nobel Energy, which discovered Leviathan and Tamar with its leading Israeli partner, Delek Group, in 2009-10, has reported finding 550 billion cubic feet of gas in its Hanna license 68 miles west of Haifa.

The Dolphin 1 well is the group's sixth straight discovery since 1999.

Noble says it has identified 12 additional prospects that likely hold vast amounts of oil as well as natural gas.