Calling the decision a "flagrant attack" on Syrian territorial sovereignty, an official from Syria's Ministry of Foreign Affairs has condemned Donald Trump's recognition of Israel's claim to the occupied Golan Heights.

The Israel Defense Force (IDF) is sending two additional brigades and thousands of army reserves to the Gaza border after a rocket was fired into Israel on Monday, prompting fears of a major military incursion. It said the rocket was fired from Rafa in southern Gaza.

Hamas or Islamic Jihad have not claimed responsibility for the attack, but Hamas reportedly told Egypt that it was fired in error and they are investigating. Egypt is reportedly attempting to negotiate a ceasefire.

Military spokesperson Major Mika Lifshitz said two armor and infantry brigades were being mobilized and that reserves would also be drafted.

Haaretz reports that "thousands" of reserves will be called up. Hamas leaders have gone underground in anticipation of an attack. The IDF said it holds Hamas "responsible for everything that happens in the Gaza Strip and from it."

Israeli military officials are meeting with the local government in the Israeli areas around Gaza communities to prepare them for expected retaliatory strikes, the Times of Israel reports.

Israel has also closed the Erez and Kerem Shalom border crossings and placed additional restrictions on fishing.

The buildup of troops suggests Gaza could face a military incursion in the lead up to Israel's election on April 9. Netanyahu has been accused of not being hard enough on Hamas by his political opponents.

© Reuters/Carlos JassoAn airplane with the Russian flag is seen at Simon Bolivar International Airport in Caracas, Venezuela March 24, 2019.

Reporter Javier Mayorca wrote on Twitter on Saturday that the first plane carried Vasily Tonkoshkurov, chief of staff of the ground forces, adding the second was a cargo plane carrying 35 tonnes of material.

The flights carried officials who arrived to "exchange consultations," wrote Russian government-owned news agency Sputnik, which quoted an unnamed source at the Russian embassy.

"Russia has various contracts that are in the process of being fulfilled, contracts of a technical military character," Sputnik quoted the source as saying.

A Reuters witness saw what appeared to be the passenger jet at the Maiquetia airport on Sunday.

Venezuela's Information Ministry did not immediately reply to a request for comment.

Russia's Defense Ministry and Foreign Ministry did not reply to messages seeking comment. The Kremlin spokesman also did not reply to a request for comment.

In December, two Russian strategic bomber aircraft capable of carrying nuclear weapons landed in Venezuela in a show of support for Maduro's socialist government that infuriated Washington.

Maduro on Wednesday said Russia would send medicine "next week" to Venezuela, without describing how it would arrive, adding that Moscow in February had sent some 300 tonnes of humanitarian aid.

Following the major weekend development of Moscow unambiguously asserting its 'red line' concerning potential US military intervention in Venezuela, for which Russia sent a military transport plane filled with Russian troops which landed in Caracas Saturday, new satellite images reveal a major deployment of S-300 air defense missile systems to a key airbase south of Caracas.

© AMNRussian S-300 missile battery delivered to Venezuela

Crucially the Russian An-124 transport plane which touched down in Caracas on Saturday carried no less than Russian General Vasily Tonkoshkurov, identified as chief of the Main Staff of the Ground Forces and First Deputy Commander-in-Chief of the Land Forces of Russia, accompanied by 99 servicemen and 35 tons of cargo.

As we reported the flight came just days after a high-level meeting in Rome last week, during which Russia reiterated a grave warning to the US - Moscow will not tolerate American military intervention to topple the Venezuelan government with whom it is allied - thus it appears Russia is taking no chances with its South American ally.

And just a day following the contingency of Russia troops landing in Caracas, Maduro's National Bolivarian Armed Forces have reportedly activated S-300 missiles after completing military drills that previously took place in February.

© ImageSat InternationalS-300 missile battery placement in Venezuela

The professional monitoring service Image Satellite International (or Image Sat) has published satellite imagery it analyzed, showing additional S-300 missiles that have been deployed to the Captain Manuel Rios Airbase in the Guarico state of Venezuela.

No doubt, the timing of the S-300 redeployment is purposeful, meant to send a strong message to Washington, though it remains unclear just how active the Russian military will be in Venezuela.

Image Sat commented on the new images: "The deployment includes five launchers and a 9S32ME multi-channel missile guidance radar (MMGR). Venezuela increases its operational readiness due to regional tension."

Perhaps paralleling the Syria situation, this could be the start of a scenario where the greater the proxy action and threats from the United States, the more Russia will slowly intervene at the behest of Maduro.

All of these developments signalling closer Russian-Venezuelan military-to-military cooperation in the face of Washington saber rattling come after three months ago the two allies held military exercises on Venezuelan soil, which the US at the time had condemned as Russia encroachment in the region.

But now with a high level Russian commander on the ground, and with Russian-made S-300s under the control of Maduro forces, it is unlikely that the US will act forcefully following the failed coup attempt of the past two months.