Siachen Glacier is situated to the

The correct option is North of Nubra Valley.

To understand why this is correct, we can analyze the geographical layout of the Ladakh region in Jammu and Kashmir (Union Territory of Ladakh):

1. Nubra Valley is a tri-armed valley located to the northeast of Ladakh valley, with Diskit as its capital. It is formed by the Nubra and Shyok rivers.
2. The Siachen Glacier is located in the eastern Karakoram range in the Himalayas, just northeast of the point NJ9842 where the Line of Control between India and Pakistan ends.
3. The waters from the melting Siachen Glacier drain into the Nubra River, which flows south-southeast to meet the Shyok River. Since the Nubra River originates from the snout of the Siachen Glacier and flows southwards, the glacier itself lies directly to the north of the Nubra Valley.

Let's also look at why the other options are incorrect:
- Aksai Chin lies to the east of the Siachen Glacier; therefore, Siachen is west of Aksai Chin, not east.
- Leh lies much further south of the glacier.
- Gilgit lies to the west of the glacier.