Why is Russia now insisting on payments for oil only in Roubles or gold?

Just one day after Vladimir Putin announced the Rouble peg with gold at Rouble 5,000 to 1 gram of gold, there have been some interesting and ominous moves. Russia has now demanded that foreign buyers of oil and gas start paying for Russian gas in roubles or in gold with immediate effect. Russia has threatened to cut off supplies of oil and gas if these conditions are not met. EU depends on Russia for over one-third of its oil and gas needs.

The US has agreed to supply Europe with LNG, but that is going to be a drop as European refiners like ENI may have to face a prolonged shutdown if the crude does not reach them on time. This has already resulted in a spike in the cost of fuel and electricity across the Europe and UK. Payment in Rouble will also blunt the sanctions imposed by the West on Russia post declaring war as it would either end up creating demand for the Russian Rouble or shifting gold from the European nations to Russia.