According to the agreement, the US, UK and Russia all agreed to protect the sovereignty and “territorial agreement” of Ukraine, meaning any Russian support for an attempt to declare Crimean independence would be in violation of their international obligations.

His words are a deliberate echo of the so-called Budapest Memorandum , signed as part of the deal that saw Ukraine give up its nuclear weapons in 1994.

Arseniy Yatseniuk called upon the members of the UN Security Council to help preserve Ukraine’s “territorial integrity” hours after armed pro-Russian separatists in Crimea took over the local parliament calling for unification with Moscow.

Ukraine’s new prime minister invoked 20-year-old international agreement as he appealed for western powers to help him resist Russian attempts to assert itself in the south of the country.

Ukraine’s new prime minister invoked 20-year-old international agreement as he appealed for western powers to help him resist Russian attempts to assert itself in the south of the country.

Ukraine’s new prime minister invoked 20-year-old international agreement as he appealed for western powers to help him resist Russian attempts to assert itself in the south of the country.

There's been a lot of loose talk about a 1994 "treaty" that obligates the US to guarantee the territorial integrity of Ukraine. As Financial Times reports, this is vastly overstating the reality of our agreement with Ukraine, which in no way says the US must come to Ukraine's defense militarily.

The three powers committed to “respect the independence and sovereignty and the existing borders of Ukraine” and “refrain from the threat or use of force against the territorial integrity or political independence of Ukraine”. Significantly, the wording suggests Russia’s insistence that Ukraine forgo an EU trade deal may have already breached the terms of the agreement. The signatories agreed to “refrain from economic coercion designed to subordinate to their own interest the exercise by Ukraine of the rights inherent in its sovereignty and thus to secure advantages of any kind”. Western diplomats are now scouring the text to check whether they are obliged to intervene in the country to prevent it from breaking up if Russia does so first. John Lough, associate fellow of the Russia and Eurasia Programme at Chatham House, the foreign policy think-tank, said: “While this does not legally oblige the UK and other western powers to intervene, they might feel morally obliged to.” He added: “Russia has already violated the spirit and letter of this agreement through the economic pressure applied to Ukraine in the run-up to the Vilnius Summit,” a reference to the November meeting when then president Viktor Yanukovich declined to sign the EU deal.

Interesting that both sides have apparently violated the agreement already, which in diplomacy usually means that the agreement would no longer be in effect.And since Russia has technically not sent in any troops thus violating Ukraine's sovereignty, there's no reason to invoke even the murky wording of the memorandum to assist Ukraine in defending its territorial integrity.

There is word that internet and telecommunications is virtually out throughout the Crimea. To attack the nodes and servers would require careful planning on the part of Russia. Clearly, Putin has had a long time to think about this move and he's being careful not to provoke the EU.

Ukraine may yet fight to maintain its territory but they won't be doing it with western help.