Saudi Arabia's portion of US debt isn't very important. They aren't even in the top 10. Belgium, Luxembourg, and Ireland all hold more.
China, Mainland 1123.5 1121.4 1138.9 1151.4 1165.1 1171.0 1179.0 1183.1 1181.9 1187.7 1176.7 1168.2 1184.9
Japan 1042.3 1036.6 1018.5 1028.0 1029.9 1035.5 1032.2 1048.9 1031.8 1044.4 1060.1 1066.0 1061.6
Brazil 303.1 311.4 313.9 317.0 317.8 299.7 300.1 299.2 294.1 286.0 272.9 265.7 256.8
Ireland 280.0 279.6 287.3 290.4 311.6 300.2 301.3 301.0 300.6 318.1 314.2 327.7 326.6
United Kingdom 272.9 258.9 263.9 276.3 272.6 271.7 274.4 265.0 262.6 263.6 250.6 243.3 249.9
Switzerland 235.0 227.5 225.2 226.9 232.0 233.1 236.3 243.4 242.2 245.4 248.0 251.1 249.6
Luxembourg 231.0 225.7 225.4 227.2 224.0 221.5 220.5 208.9 213.8 221.5 218.6 220.9 217.6
Cayman Islands 211.0 207.5 208.2 200.2 197.5 197.9 191.1 186.2 181.3 165.9 177.3 168.0 170.6
Hong Kong 196.2 189.2 185.0 192.3 193.2 194.4 196.5 191.9 194.1 196.3 196.6 194.3 194.7
Belgium 185.7 173.0 169.7 164.7 154.3 154.5 154.7 150.5 139.5 126.7 126.8 124.6 119.2
Saudi Arabia 171.6 169.9 171.3 176.1 169.5 166.8 164.3 162.2 159.9 151.2 150.9 143.7 147.4
Taiwan 157.3 155.4 162.4 166.5 163.2 164.2 162.6 164.8 168.1 170.1 170.7 175.4 180.9
India 141.3 138.5 138.2 144.0 140.6 142.6 147.3 148.9 152.8 157.0 152.9 148.6 144.7
Singapore 121.1 128.8 133.0 134.5 129.9 127.6 122.1 118.9 118.0 117.8 118.0 122.6 125.0
Korea 114.9 110.2 111.1 110.8 110.2 109.1 106.1 104.8 104.7 100.6 101.3 101.8 96.3
France 110.9 131.6 109.4 97.7 113.6 111.0 93.4 89.6 82.6 80.9 77.0 78.4 80.9
Canada 109.9
As Desk Trauma was stating, it is not about dependence on the oil any longer. We can get energy domestically. But the value of the dollar is partly based on its being the reserve currency for the world, with high circulation internationally.
The Saudis, etc. price oil in dollars, which props up our dollar. A high percentage of all international transactions have dollars on at least one side, and OPEC's willingness to price oil in dollars has helped that circulation stay high.
This is why Venezuela, Iran, Russia, China, etc. are discussing selling oil in other currencies, as it is one aspect of the dollar staying as the reserve currency.
There is debate as to what would happen if OPEC stopped trading for oil in dollars. Some think it would cause the US dollar to decline as the reserve currency, and decline in value.
Hence there is an argument that the various US administrations are acting in America's interests by being allies with the Saudis. They are also one of the nations willing to buy US debt.
I would say we need to not support the Saudis in their wars in Yemen, Syria, etc. and if our cheap goods economy declines, it is a necessary price for not supporting evil.
And of course, the Saudi leverage is somewhat offset by our troops all around the world.
As it is we use those troops to support the Saudis, and they continue to support our economy through buying our debt and continuing to list oil in dollars.