The Main cause? That Russia wasn't consecrated and so spread her errors throughout the world. Plain and simple.
Our Lady has repeatedly told us the causes and the cure at her apparitions. We get told the same each Ash Wednesday. She is still telling us. Repent and Believe the Good News.
It's all spiritual. Here in America we've left God behind. This country was built on a Christian foundation, and look how far we've come from that. God has been kicked out of our public life, and is being threatened in our private lives. We need to be on our knees asking for forgiveness and help. We can't go this alone.
I find going back to the Salvation Story of the Hebrews in the Old Testament a big help and Encouragement at the Present sad Time. God loved them, they spat in His Face and Turned Away. God sent them a Chastisement ( the word, 'Chastisement', actually means 'Purification') and they came back with their tails between their legs. This happened over and over and over again. In face the story of the Hebrews could be our own personal life story. This is our present moment in time. The Spitting in the Face of God Moment. God is about to press the Chastisement Button. In fact He already has. Acts 3:19 Repent, then, and turn to God, so that your sins may be wiped out, that times of refreshing may come from the Lord,
Isaiah 17 17 A prophecy against Damascus: “See, Damascus will no longer be a city but will become a heap of ruins. 2 The cities of Aroer will be deserted and left to flocks, which will lie down, with no one to make them afraid. 3 The fortified city will disappear from Ephraim, and royal power from Damascus; the remnant of Aram will be like the glory of the Israelites,” declares the Lord Almighty. 4 “In that day the glory of Jacob will fade; the fat of his body will waste away. 5 It will be as when reapers harvest the standing grain, gathering the grain in their arms— as when someone gleans heads of grain in the Valley of Rephaim. 6 Yet some gleanings will remain, as when an olive tree is beaten, leaving two or three olives on the topmost branches, four or five on the fruitful boughs,” declares the Lord, the God of Israel. 7 In that day people will look to their Maker and turn their eyes to the Holy One of Israel. 8 They will not look to the altars, the work of their hands, and they will have no regard for the Asherah polesa]">[a] and the incense altars their fingers have made. 9 In that day their strong cities, which they left because of the Israelites, will be like places abandoned to thickets and undergrowth. And all will be desolation. 10 You have forgotten God your Savior; you have not remembered the Rock, your fortress. Therefore, though you set out the finest plants and plant imported vines, 11 though on the day you set them out, you make them grow, and on the morning when you plant them, you bring them to bud, yet the harvest will be as nothing in the day of disease and incurable pain. 12 Woe to the many nations that rage— they rage like the raging sea! Woe to the peoples who roar— they roar like the roaring of great waters! 13 Although the peoples roar like the roar of surging waters, when he rebukes them they flee far away, driven before the wind like chaff on the hills, like tumbleweed before a gale. 14 In the evening, sudden terror! Before the morning, they are gone! This is the portion of those who loot us, the lot of those who plunder us.