If Yemen's Houthi rebels successfully blockade Saudi Arabian ships, global oil supplies could come under more pressure.

The move could increase pressure on already-strained global energy markets.

By Nayera Abdallah, Eman Abouhassira and Enas AlashrayDUBAI/CAIRO, July 20 (Reuters) - Yemen's Iran-aligned Houthis said on Monday they were imposing a naval blockade on Saudi…