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The Evangelos Florakis Naval Base explosion in Mari occurred on 11 July 2011, when 98 containers of explosives that had been stored for 2½ years in the sun on the Evangelos Florakis Naval Base near Zygi self-detonated. The resulting explosion killed 13 people, and damaged all of the buildings in Zygi, the island’s largest power station, then responsible for supplying over half of Cyprus’ electricity.
The containers of explosives on the base had been seized by the US Navy in 2009 after it intercepted a Cypriot-flagged, Russian owned vessel, the MV Monchegorsk, travelling from Iran to Syria in the Red Sea. According to US diplomatic cables leaked through WikiLeaks, the US pressured Cyprus to confiscate the shipment, as it was apparently in violation of UN sanctions on Iran.  The Cyprus Navy was given responsibility for the explosives, and it moved them to the Evangelos Florakis a month later.
The Cypriot government declined offers from Germany, the United Kingdom and the United States to remove or dispose of the material, fearing adverse reaction from Syria.  The government had instead requested that the UN effect the removal, but claimed that its request had been rejected.
As a result of the incident, the Cypriot Defence Minister and the Commander-in-Chief of the Cypriot National Guard both resigned. Angered by the government’s failure to dispose of the munitions, which had been seized in 2009, several thousand citizens staged demonstrations in the capital Nicosia and other cities every day in the week following the accident. The EU estimated the cost of the explosion could be just over 10% of the country’s economy.
Source :Wikipedia Evangelos Florakis Naval Base explosion
The US Foreign policy assessment as outlined by their Ambassador to Cyprus was as follows :
Official Cyprus is telling us their primary interest lies in fulfilling UNSC obligations and removing the cargo from the island, preferably under UN cover. However, RoC political realities — mainly, the desire to keep Moscow happy at all costs and prevent Damascus from retaliating by upgrading relations or links with the “illegal Turkish Republic of Northern Cyprus” — pose a countervailing demand that the vessel eventually reach Syria. We therefore recommend that Washington keep this in mind as it evaluates this latest proposal that Cyprus has decided to explore withthe Russians. It is difficult to gauge from here what Moscow’s position would be once the question reached the Council or Sanctions Committee. In any case, the RoC is looking for an out, and the passage of time now increases the likelihood of an unfortunate government decision to allow the Monchegorsk to sail.
On the 2nd of September 2011, the Cyprus Broadcasting Corporation citing diplomatic documents released by Wikileaks, revealed that the Cypriot government received intense pressure (with epicentre the 1747 UN Security Council Resolution, in which sanctions were imposed on Iran) before she confiscated the cargo that was heading to Syria, in early February 2009.
Previously, the US had requested from Egypt to detain the vessel within her territorial waters, stressing that “we were seeking Egypt’s cooperation in seizing the vessel’ . Egypt rejected co-operation and the US turned attention to Cyprus.
Faced with pressures that if she did not confiscate the cargo she would be violating the Resolution, Cyprus attempted to appeal to the UN Security Council for a decision on the specific case of the M/V Monchegorsk cargo. But pressures mounted to proceed to immediate application of the Resolution.
In particular, the US envoy to the UN uses the Turkish occupation and de-facto partition of the island of Cyprus as a lever to persuade the Cypriot government to toe the line with regards to automatically implementing resolution 1747 for the cargo on board M/V Monchegorsk` 
‘Wolff warned that Cyprus has a great stake in the self-enforcing nature of Security Council resolutions; imagine, he said, if countries left it to the Security Council to decide what might be allowed in terms of relations with Northern Cyprus. Wolff added that this situation is the first test of resolution 1747 and the manner in which Cyprus responds would become a precedent that could undermine the entire UN sanctions regime.’
Furthermore, the Turkish occupation and de-facto partition of the island of Cyprus is reported again in the cables as a negotiating lever, this time by Syria (SARG), to apply pressure to the government of Cyprus to let the vessel continue its voyage. 
‘No end-state other than an RoC decision to let the vessel proceed to Latakeia would satisfy the SARG, Dionysiou predicted. Should that not occur, the Syrians would look to upgrade further their relations with the breakaway “Turkish Republic of Northern Cyprus”, and lobby hard on the “TRNC’s” behalf within the OIC.’
‘Cyprus’s 2006 decision to interdict the M/V Gregorio, a vessel carrying missile radar equipment from North Korea to Syria, had caused grave damage to its bilateral relations with Damascus. The Syrians had responded by green-lighting regular ferry service between Latakeia and the “occupied” port of Famagusta in the “Turkish Republic of Northern Cyprus.” […] They worry that further government action against the Monchegorsk might provoke Damascus to take further steps to “upgrade” the “TRNC.”’
Diplomatic pressure from US (Ambassador Urbacic emphasizing the obligations of Cyprus and noting Washington’s highest-possible-level –interest ),UK (High Commissioner Peter Millet  as well as the British Ambassador ), in addition to France & Germany, via their Ambassadors  continued while Cyprus expressly needed a “a blue flag (United Nations) solution,” .
In this issue Cypriot inter-government perspectives diverge as expressed by Foreign Minister
‘Kyprianou claimed that “these people” — pointing at President Demetris Christofias and fellow AKEL party glitterati — had allowed the Monchegorsk to become an ideological, David versus Goliath affair, with “little Cyprus” naturally cozying up to Syria’s David. Such an interpretation did not bode well for a solution acceptable to the U.S., Britain, and others,’
Clinton’s State Department instructed its Embassy to intensify pressures further. It expressed concern at the highest levels of the USG, indicated that if the ship arrived in Syria the USG would not be able to portray the ROC’s actions in the most positive light, that Cyprus had an obligation to prevent the use of a Cypriot flagged vessel from participating in the Iran-Syria transaction and it should stop this shipment in order to protect the integrity and sound reputation of its ship registry 
To put the latter statement into perspective, Cyprus has the fourth-largest ship registry in the world  and its significance in the Island’s economy cannot be stressed enough.
The unrelenting pressure continued:
‘Without its desperately-sought “UN cover,” we believe that Cyprus will continue to resist with all means available the off-loading of the Monchegorsk in Limassol. We also understand, however, that the EU is turning up the heat on the RoC to take action in line with EU Common Positions. Success in Brussels would be the best outcome to the Monchegorsk affair.’ 
till Cypriot government first stated that ‘will not be able to withstand the pressure much longer, and has to find a way out’  and then capitulated with the offloading of the vessel’s cargo . A few weeks later Clinton’s US State Department drafts proposed text for the UN Iran Sanctions Committee letter thanking Cyprus, with further guidelines to them to retain the cargo 
Cyprus’s final compliance, albeit half-hearted, came only after a full-court international press from the UN Security Council and EU. Cyprus did not win any favours with the US or UN for its acquiescence. Within weeks of unloading the cargo, FM Kyprianou pending visit to the US with the Island’s efforts for Unification on the agenda, the US Ambassador in Nicosia explains that the UN envoy Alexander Downer recently argued “it is time to inject some uncertainty in Greek Cypriots’ minds that this cannot go forever”. He then goes on to recommend that US should support Downer in his campaign, further suggesting ways and means of pressuring Cyprus and Greece to make a deal, whilst berating the Cypriot president’s Non-Aligned Movement aspirations. 
The significance of the diplomatic cables is that they threw timely light into the diplomatic pressures and negotiations behind the decision to accept the dangerous cargo onto Cyprus.
(Greek) The Diplomatic Game
 09NICOSIA93, Monchegorsk: MFA seeling Legal options, Presidency evaluating disposition options – Embassy Nicosia (Cyprus), WL release 27th June 2011
 09CAIRO102 Egypt: Requesting GoE Seizure Of M/V Monchegorsk — Embassy Cairo (Egypt), WL release: 1st Sep 2011
 09USUNNEWYORK79, Iran: P3 Urges Cyprus To Prevent Arms Transfer In Violation Of UN Sanctions , WL release: 1st Sep 2011
 09NICOSIA96, Cypriots Still Weighing Options On Monchegorsk — Embassy Nicosia (Cyprus), WL release: 27th June 2011
 09NICOSIA58 Cyprus Washing Hands of M/V Monchegorsk? – Embassy Nicosia (Cyprus), WL release 25th of June 2011
 09NICOSIA98, M/V Monchegorsk: Cyprus Insists On Un Cover — Embassy Nicosia (Cyprus), WL release 27th June 2011
 09STATE7877 Engaging the ROC regarding the M/V Monchegorsk – US State Department, WL release 27th of June 2011
 Wikipedia Economy of Cyprus
 09NICOSIA104 Monchegorsk: Cypriots beginning to squirm – US State Department, WL release 27th of June 2011
 09NICOSIA106 Cyprus fleshing out Malta idea Cover — Embassy Nicosia (Cyprus), WL release 27th June 2011
 09NICOSIA125 Cargo offloaded — Embassy Nicosia (Cyprus), WL release 27th June 2011
 09STATE30114 USUN Instruction: Iran Sanctions Committee efforts on Montchegorsk
 09NICOSIA272 Cyprus: scenesetter for FM Kyprianou’s April 20 visit — Embassy Nicosia (Cyprus), WL release 27th June 2011