The natural gas discoveries in the Mediterranean and repercussions of the Arab Spring yielded significant developments in the regional architecture of the Eastern Mediterranean Basin. Chief among them are the trilateral relationship among Israel, Greece and Cyprus and the regional gas forum launched in Cairo in early 2019 with the participation of seven Middle Eastern and European members (including Israel and the Palestinian Authority), with US and European support. Turkey is not a participant in any of these new constellations, viewing them as Mediterranean frameworks designed to exclude it in light of the circumstances in the region.Turkey recently took a surprising counter measure. On November 27, it signed two agreements with Libya’s al-Sarraj government – one on military cooperation and the other marking the economic maritime borders between the two countries. The maritime agreement generated much regional and international interest, prompting condemnation by various states. Turkey is not a signatory to the UN’s Law of the Sea and has a different interpretation regarding the distribution of economic waters among the Mediterranean coastal states. It challenges the rights of Cyprus and the Greek Islands, including Crete, to economic waters of their own and therefore argues that its agreement with Libya complies with the rules of international law. Greece and Cyprus are leading the international opposition to the Turkish-Libyan agreement. Greece sent two missives to the UN, rejecting out of hand the agreement and calling on the Secretary General and the Security Council to discuss the issue. The EU, too, has condemned the agreement and backed its two Hellenic member states in the dispute. Israel, for its part, expressed public and clear support for the Greek position. Russia chose to react mostly to the military cooperation agreement, which, according to the Foreign Ministry in Moscow constitutes a “grave breach of the arms embargo on Libya”.It should be noted that Libya is a divided state, with one government in Tripoli headed by Fayez al-Sarraj, which has won de facto recognition by the international community, and another headed by Gen. Khalifa Haftar, which enjoys the support of Egypt and the United Arab Emirates (but is also “flirting” with other states and entities, including Russia), located in Tobruk. This explains international concern over growing escalation in the Libyan civil war, especially given the involvement of many foreign players.What, then, is the point of the Turkish move and whom is it meant to challenge?Both Libyan-Turkish agreements, and especially the one delineating their maritime borders, are designed to challenge the anti-Turkish constellation that has emerged in recent years and currently includes concrete energy-related cooperation. The agreements, as President Recep Tayyip Erdogan clearly stated, are designed to signal Turkey’s intention to insist on its rights in the region. Turkey is also seeking to convey its message by drilling in Cypriot economic waters (which, as mentioned, Turkey does not recognize). The latest Turkish moves mainly address Greece and Cyprus (over the interpretation of economic waters), but also Egypt. A deep and wide-ranging rivalry exists between Egypt and Turkey since al-Sisi assumed power. Turkey’s Libyan move is generating great anger in Cairo, and Egypt is expected to respond with intensive measures vis-à-vis the Libyan arena, perhaps even with an effort to overturn the agreements (which are defined as “memoranda of understanding,” a fact which has raised various interpretations regarding their legally binding status).Israel, too, views the agreements as measures of Turkish defiance, as expressed in Erdogan’s statement that Israel, Greece, Cyprus and Egypt would not be able to make any move in the Eastern Mediterranean Basin without Turkish approval. The Turkish move poses an additional challenge to the ambitious plans for a gas pipeline from Israel to Europe that will now have to go through territorial economic waters to which Turkey lays claim. Israel therefore immediately took a stand supportive of Greece. However, it is important to point out that Israel is currently in what can be called “the second circle” of those to whom the Turkish move is addressed. As mentioned, marking the economic waters between Turkey and Libya directly clashes with the Greek-Cypriot stand and interpretation. It challenges, creatively it must be said, the new Mediterranean architecture, with Israel at its center to a large extent and which isolates Ankara (even though Israel insists that its regional alliances are not directed against any country). However, the November 2019 incident between an Israeli research vessel and Turkish navy ships, along with the summoning of Israel’s top diplomat in Ankara to the Turkish Foreign Ministry over the Turkish-Libyan agreement, move Israeli involvement up a notch and will force Israel to consider a more direct reaction vis-à-vis Ankara.In any case, we can expect to witness extensive diplomatic activity aimed at ensuring that the Turkish-Libyan agreements do not overly exacerbate relations in the region, which are already at risk of escalation, and the situation on the ground in Libya. Russia’s moves (Erdogan was quick to appeal to Moscow on the issue) will be especially interesting given its complex and often contradictory links with the two sides in Libya, although it views the Syrian arena (where it has close ties with Turkey) as more important. Egypt’s reaction will also be of great interest, given its central role in the new architecture of the Eastern Med Basin and major interests in the Libyan arena.Israel, for its part, would do well to adhere to the regional relationship painstakingly built in recent years, with considerable success, and to support the position of its allies in the Eastern Mediterranean. The current architecture serves Israeli interests well, and in principle, its public position that avoids highlighting Ankara’s confrontational stance leaves it sufficient room for maneuver in the current circumstances. Turkey’s direct and more assertive messages are now putting to the test Israel’s decision to avoid direct public clashes with Ankara. Israel has to hone its position now by emphasizing the regional alliances, without overly exacerbating the already tense and complex situation in the Eastern Mediterranean Basin.The writer is a policy fellow at Mitvim – The Israeli Institute for Regional Foreign Policies, and formerly the Israeli ambassador to Cyprus.